Do I dare take a sander to a jointer infeed & outfeed table?

["Patrick G Rainsberger"]

Has anybody ever taken a RO sander to the bed of a jointer to knock down the high spots?
I have an 8” 74” jointer that is perfectly flat in the center 54”. The last 10” of the infeed and outfeed table rise .005 to .006”. When I edge joint two board 27” long they are perfectly straight when put together. When I edge joint two board 36” or longer and put them together they touch in the center but don’t on the ends. I can slip a .007 feeler gauge between The two 36” boards on the end. I’m using a veritas 36” steel straightedge and a oneway multi gauge as measuring devices.
I started a thread last week ‘Grizzley Jointer Fence II’ The thread ended before I had figured out what was happening with the longer boards. The end of the board is being held above the flat part of the infeed table while the other end of the board is going through the cutter. When the board comes off the high end of the infeed table the end of the board that just went through the cutter is now raised off the table. When the board is going off the end of the outfeed table, the cutter is cutting deeper into that end of the board. I can put two boards through the cutter 25 times each and I never can get them to touch on both ends.
Would you start with 320 grit? Any ideas?
The Jointer is out of warrantee.

[Larry Edgerton]

I give my tables a light working over once in a while, but I use a steel sanding board used for fairing the flats on race boats, basically a 50 pound sanding board. Your situation needs more control.

Couple of things. I am sure that it was flat right after they milled the surface. But I'm sure the aging process is the distance from the foundry to the assembly area. Cast Iron moves as it ages. A perfectly flat piece will move as it self relieves internal stresses. Used to be up in Canada where they make generals there was a field full of casting that werer there to age, after a couple of years they would bring them in and machine them. People generally don't do that any more.

So.... The big question is, is it done moving? Anyway, I would have it, and by it I mean the infeed and outfeed tables shot peened, and then ground flat, if your machine can be readjusted. Shot peening will relieve the internal stresses. We do it to racing parts to improve stability and durability.

I have had to do this to a couple of tools, my Delta DJ20 was one, and the fence on my favorite chop saws, the old Delta cast iron, all warped with age.

Or, you could just get bigger clamps..........

Larry

[Chris Fournier]

The short answer to your question is ABSOLUTELY NOT!

This is a rather complicated topic and our information is not complete but I think that you have many more conventional options to solve your problem.

Are you certain that your two tables are not flat? I mean each individual table. I'd bet that they're okay.

I think that your problem is with the cutter height relative to the outfeed table. I like my cutter knives to be a couple thousandths of an inch higher than the outfeed table. Where are your knives relative to the outfeed table - high, low, co-planer? THIS IS LIKELY THE KEY TO YOUR PROBLEM.

Check this out and get back to us. We'll have you jointing straight edges in no time and all you have to do is spin some wrenches - no sanding.

[Dan Friedrichs]

The short answer to your question is ABSOLUTELY NOT!


+1 (sorta) - it can be done if in fact your tables are not each individually flat. Like Chris, I don't believe that yours are.

First things first: establish if the tables are flat, and if not, how un-flat they are. Take your straight edge, place it on one table, and try sliding feeler gauges under it. Mark (with a sharpie) spots that are low (and how low they are). Move the straightedge all over the table, trying to find the largest gap you can slide a feeler gauge under.

If you find that the largest gauge you can slide under the straightedge is 0.008" or less, you're good (that's actually Delta's flatness spec on the venerable DJ-20, which it sounds like you have a clone of). Once you've established (for sure) that your tables are sufficiently flat, you can move on to determining what adjustments need to be made to correct whatever alignment problem you most likely have.

["Patrick G Rainsberger"]

Larry,
I bought my Grizzley GO 593 in 2007. It's probably through moving. What is shot peening? Where would I get this done and would this process of shot peening and grinding cost more than the Jointer is worth?

[Carl Beckett]

If I understand what you wrote correctly, you are getting 0.007" gap between the ends of two 36" boards. This is 0.0035" per side.

And if this is while the opposite ends are touching, you can halve that again.

It doesnt sound like a lot. Im surprised that the clamping force doesnt pull this down.

But to your question - I wouldnt use the RO until you run through the other checks per the responses here.

(Im going to go check how straight I can get boards out of my jointer now.....

["Patrick G Rainsberger"]

The short answer to your question is ABSOLUTELY NOT!

This is a rather complicated topic and our information is not complete but I think that you have many more conventional options to solve your problem.

Are you certain that your two tables are not flat? I mean each individual table. I'd bet that they're okay.

I think that your problem is with the cutter height relative to the outfeed table. I like my cutter knives to be a couple thousandths of an inch higher than the outfeed table. Where are your knives relative to the outfeed table - high, low, co-planer? THIS IS LIKELY THE KEY TO YOUR PROBLEM.

Check this out and get back to us. We'll have you jointing straight edges in no time and all you have to do is spin some wrenches - no sanding.


Check the thread 'Grizzley Jointer Fence II' 4/13/11 I went all through your concerns.

[Bob Wingard]

As already posted ... IF your two tables are EACH FLAT, but out of alignment, you have other choices which are basically free. If one table is dished slightly, shim that table so the dish is in the center of the overall alignment ... do the same for the other table, and you will reduce the error by more that half.

If you REALLY want to tackle the surface with something ... ask around about scraping rather than sanding the table(s) ... that's how machine lathe beds were trued & refinished back in the day when there were skilled tradesmen who knew the art. Failing that, consider obtaining a long, flat large extrusion that you could use as a giant sanding block ... affix some very coarse abrasive to it, and have at it. That would, however be my last course of action.

["Patrick G Rainsberger"]

+1 (sorta) - it can be done if in fact your tables are not each individually flat. Like Chris, I don't believe that yours are.

First things first: establish if the tables are flat, and if not, how un-flat they are. Take your straight edge, place it on one table, and try sliding feeler gauges under it. Mark (with a sharpie) spots that are low (and how low they are). Move the straightedge all over the table, trying to find the largest gap you can slide a feeler gauge under.

If you find that the largest gauge you can slide under the straightedge is 0.008" or less, you're good (that's actually Delta's flatness spec on the venerable DJ-20, which it sounds like you have a clone of). Once you've established (for sure) that your tables are sufficiently flat, you can move on to determining what adjustments need to be made to correct whatever alignment problem you most likely have.


Dan,

That's just what I did. The last 10 inches of each table is where I was able to slip the feeler gauge under the straightedge. As I moved the straightedge closer to the edge, I was able to slip a thicker feeler gauge under until I reached the edge of the table. When the straightedge was 1" from the edge of the table I was able to slip .005 - .006" under the straightedge.

[Dan Friedrichs]

By "last 10 inches", do you mean closest to the cutter, or farthest away from the cutter?

Either way, I don't think it matters - 0.006" is not enough to be affecting your jointing results. As I said earlier, Delta's factory specs allowed for 0.008" on a DJ-20 - yours is within spec. You have a different alignment problem, not a flatness problem.

[ray hampton]

why do a cast iron table move in this manner ? maybe a bolt bearing against the table, could the problem be cause by your boards warping slightly

["Patrick G Rainsberger"]

By "last 10 inches", do you mean closest to the cutter, or farthest away from the cutter?

Either way, I don't think it matters - 0.006" is not enough to be affecting your jointing results. As I said earlier, Delta's factory specs allowed for 0.008" on a DJ-20 - yours is within spec. You have a different alignment problem, not a flatness problem.

Dan,

Both tables rise starting 10" from their ends. The rest of both tables are perfectly flat. I set both tables at 0 on my oneway height gauge. I checked the cutterhead and set it .001 above the outfeed table. I checked the cutterhead to both tables (from the fence to the edge) and a random measurement of carbide cutterheads were within .001. Both tables were dead flat with each other 27" out from the cutterhead.

[shane lyall]

Sounds like there not co-planer to me. Sorry but I didn't see the other thread so if you checked this please nevermind. I'm no expert but I have the Delta model and mine is within about .005 as best as I can tell.

[Dan Friedrichs]

So the tables each have a dip at the ends farthest from the cutterhead? If so, it seems unlikely that BOTH tables would be like that. Are you SURE your measurement procedure is perfectly correct? These are hard measurements to make - I've personally never been able to master the use of feeler gauges, and instead, mount a dial indicator to the end of my straightedge for this sort of thing. I suspect both of your tables need to be adjusted so that their ends are up higher.

Additionally, if in fact your tables are both dipping at the ends, this shouldn't affect your jointing results AT ALL. Think about it - if the outfeed table is dipping down, how does that contribute to a board that isn't straight? If might, if you are using the jointer incorrectly - you might want to review your technique, making sure that once the board passes the cutterhead, you are applying firm downward pressure at the area immediately after the cutter. Any dip in the outfeed that is towards the end shouldn't matter, if you are applying sufficient pressure while feeding the stock.

[Dan Friedrichs]

Also, take a look at this page:
http://home.usmo.com/~rfwoodworking/jointer.html

I'm not sure it's immediately relevant to your problem, but it's an interesting visualization of how jointer coplanarity problems manifest themselves.

["Patrick G Rainsberger"]

So the tables each have a dip at the ends farthest from the cutterhead? If so, it seems unlikely that BOTH tables would be like that. Are you SURE your measurement procedure is perfectly correct? These are hard measurements to make - I've personally never been able to master the use of feeler gauges, and instead, mount a dial indicator to the end of my straightedge for this sort of thing. I suspect both of your tables need to be adjusted so that their ends are up higher.

Additionally, if in fact your tables are both dipping at the ends, this shouldn't affect your jointing results AT ALL. Think about it - if the outfeed table is dipping down, how does that contribute to a board that isn't straight? If might, if you are using the jointer incorrectly - you might want to review your technique, making sure that once the board passes the cutterhead, you are applying firm downward pressure at the area immediately after the cutter. Any dip in the outfeed that is towards the end shouldn't matter, if you are applying sufficient pressure while feeding the stock.

Dan,

Both ends turn up like a set of skis.

[Chris Rosenberger]

Dan,

Both tables rise starting 10" from their ends. The rest of both tables are perfectly flat. I set both tables at 0 on my oneway height gauge. I checked the cutterhead and set it .001 above the outfeed table. I checked the cutterhead to both tables (from the fence to the edge) and a random measurement of carbide cutterheads were within .001. Both tables were dead flat with each other 27" out from the cutterhead.

Patrick,
I did it on a Powermatic 60 jointer. I did not have as much of a bow in the table to remove as you do, but It worked for me.

["Patrick G Rainsberger"]

Check the thread 'Grizzley Jointer Fence II' 4/13/11 I went all through your concerns.

Chris, I don't know how to add a different thread to my message. On looking back, my message did seem a little rude. Sorry

["Patrick G Rainsberger"]

Patrick,
I did it on a Powermatic 60 jointer. I did not have as much of a bow in the table to remove as you do, but It worked for me.

Chris,

Did you have the same problem when jointing as I before you sanded the table. What was your procedure? I'm still waiting for Larry to respond but I'm interested in what you said you did to solve this problem

[Chris Fournier]

People flatten cast iron machine tool surfaces every day, brand new machines and reconditioned used pieces - they do not use random orbital sanders. As Bob mentioned they use a technique called scraping which is very precise; chasing flatness by the fraction of a thousandth of an inch with each small adjustment. Your jointer is not worth a ton of money and even having it sent out to be surface ground would likely not be economical for you. Checking for flatness is simple enough but your observations are only as good as your measuring tools. What is the straight edge that you are using? Is is a carpenters level or an expensive ground tool steel straight edge worth a few hundred dollars with a know flatness over its length?

Check out any metal machinists forum and search "scraping" and you'll quickly learn how involved it is to achieve what you are proposing - with proper tools and techniques!

Occam's Razor applies to your situation in spades.

["Patrick G Rainsberger"]

People flatten cast iron machine tool surfaces every day, brand new machines and reconditioned used pieces - they do not use random orbital sanders. As Bob mentioned they use a technique called scraping which is very precise; chasing flatness by the fraction of a thousandth of an inch with each small adjustment. Your jointer is not worth a ton of money and even having it sent out to be surface ground would likely not be economical for you. Checking for flatness is simple enough but your observations are only as good as your measuring tools. What is the straight edge that you are using? Is is a carpenters level or an expensive ground tool steel straight edge worth a few hundred dollars with a know flatness over its length?

Check out any metal machinists forum and search "scraping" and you'll quickly learn how involved it is to achieve what you are proposing - with proper tools and techniques!

Occam's Razor applies to your situation in spades.

Chris,

I used the 36" Steel Veritas Straightedge. It's plenty accurate for this application.

http://www.leevalley.com/en/wood/page.aspx?cat=1,240,45313&p=56676

[Rick Lizek]

I have had jointer beds ground in machine shops. It's not something to be done casually by an inexperienced person and I would not wast the time with a random orbit sander as it would take too long to do anything and by the time you did it would be far worse as the random orbit sander is totally unsuited for the application.

The tolerances sound normal to me and I repair machinery as part of my work. I normally use a 6' machined straight edge to check that length of bed. A 36" straight edge is too short to be usefu on a 72" bed. Could be part set up and operator error from here. As simple as a jointer is, most of the time it's a slight set up problem, such as the knives are a bit too low to the outfeed table. Not stating clearly what kind of table set up you have shows a lack of understanding of the jointer set up. Paralleogram or Dovetailed ways? Not feeding the board correctly can cause the same issues. Are you keeping your hand pressure on the outfeed table as soon as you get the edge of the board over the cutter. I've seen a lot of conflicting info on just feeding the board and even as simple as the crown up or down. It's very difficult to explain how to properly joint a board verbally and even with pictures. For many, it takes a hands on lesson in person.

[Norman Hitt]

Boy, reading this thread, I can't believe so many people apparently cannot READ. He said in the very first post that the first 27 inches going away from the cutterhead on EACH table was flat and Then both of them started to RISE, (NOT Dip) on out to it's respective end. He also reaffirmed this in his answers. I'm not trying to be grumpy or start any fights either, but just ask everyone to slowly reread his posts and listen to what he is saying.

One other thing, IF, you lay a 36" precision straight edge on the tables with it centered over the cutterhead and there is NO gap and then start sliding it toward the end of either table and when one end of the straight edge gets within 10" of the end of the table and a gap starts appearing beneath the straight edge that increases as you move on to the end, you can be assured that the table has a curl "UP" in that last 10 inches.

I HOPE this helps, Patrick.

PS: I lapped the outfeed table one winter, (a little at a time) on an old 6" jointer that had a Fixed outfeed bed, and it finally came out nice, but it was a SLOW process, and I definitely wouldn't do that again, but it was my Dad's old jointer with lots of sentimental value. I used Emery cloth glued on the edge of a heavy cast aluminum alloy bricklayers level that I checked for flatness.

[Larry Edgerton]

Boy, reading this thread, I can't believe so many people apparently cannot READ. He said in the very first post that the first 27 inches going away from the cutterhead on EACH table was flat and Then both of them started to RISE, (NOT Dip) on out to it's respective end. He also reaffirmed this in his answers. I'm not trying to be grumpy or start any fights either, but just ask everyone to slowly reread his posts and listen to what he is saying.

.

You noticed that too......

Patrick. I am not sure on costs as a friend of mine is an engine builder and everything I needed was at my disposal for free. Well, I did help him build some fence for his cattle....

Shot peening is just a sandblaster basically that shoots little steel balls about the size of a bb. Nothing fancy, should be cheap. Its done on rods and cranks to get rid of any internal stresses. Surface grinding was free as well, so can't help you there either. Scraping is something I have heard of but have no idea, so grinding was better for me. Maybe you could find an old machinist to help you out in that respect? I am in a resort area, not so many machinists around that I am aware of here, so I went with what I had available.

For my smaller parts I use 3M stickit paper stuck to the top of a known flat surface, my old PM66, and rub the pieces back and forth until they show flat. Works for small cast iron fences that are not too large.

There is more than one solution to almost every problem, and this is just how I solved my problem.

Larry

[Larry Edgerton]

So the tables each have a dip at the ends farthest from the cutterhead? If so, it seems unlikely that BOTH tables would be like that.
.

Actually, that is contrary to logic. Both tables were cast at roughly the same time with roughly the same material, in molds that were roughly the same shape, and probably had about the same lead time to being machined. Logic would say that they are more likely to have the same problem. Cast iron moving as it ages is not an oddity, it is almost a certianty. That is why some machines such as my SCM planer use cast steel instead of iron. Cast iron engine blocks are almost always out, and in racing applications need to be rebored to center, cam and crank journals need to be line bored, before they are good enough for high performance applications. These were not machined wrong at the factory, but moved as they seasoned.

Larry

[Chris Fournier]

I don't think that its a reading comprehension problem. The difficulty is making sure that the OP and the rest of us are on the exact same page and that we all understand how he got to his conclusions. It is no small matter recommending that someone take a RO sander to his equipment to tune it up by thousandths of an inch! (There was a thread a little while ago where the OP asked for help and people asked him if he had checked out A - the obvious and simplest cause of his problem. He assured everyone that he had so out came the less obvious solutions and pulling at straw theories. A respondent to the now mature thread asked once again "have you really checked out A?" The OP then came back and said "Oh I was wrong, it was A all the time. This is why we have the questions on this thread, not because we're stupid and can't read.)

Seasoning iron castings out in fields is largely a thing of the past - I know, the good ol' days... Now raw castings go to a heattreeating facility where they spend time in an oven and are subjected to a "heat recipe" that is designed to relieve casting stresses. And what is a typical casting stress? The outside of a casting cools first and as it does it shrinks around the still hot interior - which ultimately cools and shrinks too but the outside "skin" is now in tension. This is a very simple explanation of course.

I do not think that shot peening would be a good solution in this situation. Shot peening is not necessarily a stress relieving process, though it often is. Shot peening puts the surface of an object in compression which then makes the object tougher when it comes to tension - cracking. Heat treating would be a more common process to deal with cast iron pieces like our jointer tables. Tension from casting + compression from shot peening = stress relief.

But before we all believe that the problem with these tables is residual stress in the iron castings and then proceed in this direction we should really consider the possibility that the present casting surface is the result of poor surface grinding - which is entirely possible! While no pro I have a surface grinder for my own projects and I can assure you that I could make tables like the OP's if I wasn't careful. Careless grinding intoduces heat which causes dimensional change and now you are grinding materila that you have just grown so to speak!

If these tables really get to you send them out to a reputable shop for surface grinding but get a quote first!

[Russell Sansom]

Just for the fun of the discussion, here's a map of my DJ-20. This was carefully done with a two 5' straightedges, straight to <.002" along their lengths. These results were repeatable, so I'm confident they are close to correct.
The isobars indicate "depressions" in the table top. I've always thought that this "lake bed" geography is typical of cast iron tables.
The shorter off-feed table has a "lake bed" that is only .0025" deep, which is consistent with my beliefs about how CI tables cool and stress ( but I'm enough of a scientist to understand that my beliefs aren't true simply because of these data ).
I wonder if Chris's tables actually "flip up" at the ends, as opposed to this pattern, but I don't have first hand experience with all this besides setting up CI tables over the years.

I don't think scraping is an appropriate means to remove this much iron.
One more thing. In order to remove the tables for surface grinding you'd need to completly disassemble the jointer. Even if you're a very fluent mechanic, it's going to take 3-5 hours.

[J.R. Rutter]

I would stick some sand paper on the end of a straight board, lay the whole board on the jointer table with the abrasive over the high spot, and lightly sand away. Recheck for flatness often. ROS is not the tool for this.

["Patrick G Rainsberger"]

[QUOTE=Norman Hitt;1686592]Boy, reading this thread, I can't believe so many people apparently cannot READ. He said in the very first post that the first 27 inches going away from the cutterhead on EACH table was flat and Then both of them started to RISE, (NOT Dip) on out to it's respective end. He also reaffirmed this in his answers. I'm not trying to be grumpy or start any fights either, but just ask everyone to slowly reread his posts and listen to what he is saying.

One other thing, IF, you lay a 36" precision straight edge on the tables with it centered over the cutterhead and there is NO gap and then start sliding it toward the end of either table and when one end of the straight edge gets within 10" of the end of the table and a gap starts appearing beneath the straight edge that increases as you move on to the end, you can be assured that the table has a curl "UP" in that last 10 inches.

I HOPE this helps, Patrick.

Thanks Norman,

I'm not always the best communicator and tend to blame myself if people don't understand what I'm saying, but this time I thought I had covered all the bases. I admit I did not indicate the jointer had dovetail ways, but I did give the make and model number.

The idea of sanding the last 10" of these table beds in order to keep the stock from riding high while it enters the cutterhead and riding high again as it exits the cutter head does not warrant this level of discourse. If I sand .010" off, what would be the harm? I would never try this on my tablesaw, bandsaw, planer or the engine heads of my car. This was specifically about the last 10" of the jointer table only.

I learned a lot from this thread and appreciate all of your concerns. I guess that's what the Creek is all about.

Thanks again

[Frank Drew]

I'm not always the best communicator and tend to blame myself if people don't understand what I'm saying

Patrick, I think I understood you right off; Norman is right, IMO, about people posting without reading carefully. Additionally, I'm surprised that so many posters seemed to jump to the conclusion that you're unable to take an accurate measurement, don't know what you're talking about, and know nothing about jointers. All that with no evidence at all (the jointer's not in their shop, after all) just the curious assumption that modern day machine parts simply can't be off in the way you describe. :confused:

[Dan Friedrichs]

I think I was one of the ones who jumped to the incorrect conclusion - forgive me; but sanding cast iron unnecessarily (or incorrectly) could be a quick way to completely ruin an expensive jointer.

That said, if you are 100% sure that both ends rise slightly up (despite it being somewhat unlikely that both would do it the same direction and in exactly the same amount), as long as you don't sand near the cutterhead at all, the worst thing you could do is sand too much off, but that shouldn't hurt your jointing operation.

I'll say again, though, that 0.005" is WELL-WITHIN accepted specs. If you bought a brand-new one and had this problem, NO manufacturer would offer you any remedy. You should not be seeing a problem in jointed boards that can't be fixed with a bit of clamping pressure with that small of an error.

If the error really bothers you, though, I'd first try to adjust the beds such that the ends get lowered 0.005" (even if that means the tables will now be non-coplaner), and see what that does to the error.

["Patrick G Rainsberger"]

One last reply. I'm not going to use my RO sander. You have all talked me out of using it, but I am thinking of using 3M Stickit paper on my Granite Surface Plate that I picked up at Woodcraft. The plate is about 15 lbs. It came with a report card that rated it flatness at .001 mm. It measures 9" X 12" X 2". If I can't get 3M Stickit paper that size I'll have to glue a sheet of sandpaper to it. If I keep the sanding to the outside edge of the tables only, I don't think I'll ruin my jointer.
http://www.woodcraft.com/Product/2004864/7535/Granite-Surface-Plate.aspx

again--thanks

[Norman Hitt]

Patrick, I kinda have doubts about how much control you will have using that surface plate, and I have a suggestion you "Might" want to consider. To simulate what I did on my old jointer, AND to control where you are cutting so as to cut down ONLY the high area without dipping off toward the end or sanding any of the flat area, I suggest the following, (which is similar to what JR suggested).

Go to the Borg and purchase about 30" of the 1" or 1 1/2" steel square tubing, and get a small roll of "GOOD quality" 80 and 120 grit Emery cloth, (or sheets you can cut into strips if you can't get a roll.
Cut a strip about 18 or 20" long and glue it to one side of the square tubing, (starting at one end.

Next, cut about a 4" long strip and glue it on the same side of the tubing to the other end, BUT glue it with the abrasive against the tubing. This will give you a cutting surface to work on the high end AND a straight line contact point on the other end that will also keep the tubing from scratching the jointer bed in the flat area.

Next: Use a black magic marker or sharpie and draw a line across the jointer bed at the end of the dead flat area. Now the work starts,:D

Make all your strokes back and forth in line with the length of the jointer bed, keeping the downward pressure evenly spread over the length of the square tubing. Check your progress occassionally with your straight edge so you can make any corrections if needed.

When you see scratch marks getting close to the line you drew across the Jointer bed, you are getting close to flat and need to closely monitor your progress by dragging your straight edge across and looking for light under it (gap) and change to a finer grit to finish, see below).

I would put the 120 (or whatever finer grit you get on another side of the tubing, (In the same manner, including the piece at the other end), and continue with this grit until it is flat, and it should be reasonably polished with this grit.

Anyhow, this is just a suggestion of how I would do it to assure no dips due to lack of control of the grinding media, and as I said before, it did work for me, but good luck with whatever method you decide on.

Let us know how it all works out.

Ps: I suggest using the Emery cloth because I was always taught (and believe) Sandpaper is for wood, but Emery cloth is for metal. I do know it holds up better.

[Chuck Wintle]

Has anybody ever taken a RO sander to the bed of a jointer to knock down the high spots?
I have an 8” 74” jointer that is perfectly flat in the center 54”. The last 10” of the infeed and outfeed table rise .005 to .006”. When I edge joint two board 27” long they are perfectly straight when put together. When I edge joint two board 36” or longer and put them together they touch in the center but don’t on the ends. I can slip a .007 feeler gauge between The two 36” boards on the end. I’m using a veritas 36” steel straightedge and a oneway multi gauge as measuring devices.
I started a thread last week ‘Grizzley Jointer Fence II’ The thread ended before I had figured out what was happening with the longer boards. The end of the board is being held above the flat part of the infeed table while the other end of the board is going through the cutter. When the board comes off the high end of the infeed table the end of the board that just went through the cutter is now raised off the table. When the board is going off the end of the outfeed table, the cutter is cutting deeper into that end of the board. I can put two boards through the cutter 25 times each and I never can get them to touch on both ends.
Would you start with 320 grit? Any ideas?
The Jointer is out of warrantee.
Patrick,
Good luck with the jointer tables...just a question but have you let anyone else measure to confirm your findings? not saying your measurements are incorrect but an independent look might reveal a different situation.

[Frank Drew]

For what it's worth, the results that Patrick says he's getting when jointing longish boards (too much taken off the ends) are just what you'd expect with the tables "sloped" up at their far ends, as he describes.

["Patrick G Rainsberger"]

Patrick, I kinda have doubts about how much control you will have using that surface plate, and I have a suggestion you "Might" want to consider. To simulate what I did on my old jointer, AND to control where you are cutting so as to cut down ONLY the high area without dipping off toward the end or sanding any of the flat area, I suggest the following, (which is similar to what JR suggested).

Go to the Borg and purchase about 30" of the 1" or 1 1/2" steel square tubing, and get a small roll of "GOOD quality" 80 and 120 grit Emery cloth, (or sheets you can cut into strips if you can't get a roll.
Cut a strip about 18 or 20" long and glue it to one side of the square tubing, (starting at one end.

Next, cut about a 4" long strip and glue it on the same side of the tubing to the other end, BUT glue it with the abrasive against the tubing. This will give you a cutting surface to work on the high end AND a straight line contact point on the other end that will also keep the tubing from scratching the jointer bed in the flat area.

Next: Use a black magic marker or sharpie and draw a line across the jointer bed at the end of the dead flat area. Now the work starts,:D

Make all your strokes back and forth in line with the length of the jointer bed, keeping the downward pressure evenly spread over the length of the square tubing. Check your progress occassionally with your straight edge so you can make any corrections if needed.

When you see scratch marks getting close to the line you drew across the Jointer bed, you are getting close to flat and need to closely monitor your progress by dragging your straight edge across and looking for light under it (gap) and change to a finer grit to finish, see below).

I would put the 120 (or whatever finer grit you get on another side of the tubing, (In the same manner, including the piece at the other end), and continue with this grit until it is flat, and it should be reasonably polished with this grit.

Anyhow, this is just a suggestion of how I would do it to assure no dips due to lack of control of the grinding media, and as I said before, it did work for me, but good luck with whatever method you decide on.

Let us know how it all works out.

Ps: I suggest using the Emery cloth because I was always taught (and believe) Sandpaper is for wood, but Emery cloth is for metal. I do know it holds up better.

Norman,

Thanks for the details. After I posted my 'One last reply' I realized that the surface plate might give me a super flat surface, but I wouldn't have control with such a large plate. I then thought of my Norton water stones, they go from 220 to 8000, but I like your idea much better and will post my results when I'm done.

[David Giles]

Be sure to thoroughly wet the surface first to raise the grain before sanding.

Sorry, couldn't resist.

[Andrew Pitonyak]

Be sure to thoroughly wet the surface first to raise the grain before sanding.
Won't be required if he uses cast-iron-sanding-sealer, either that or use a hand plane to shave it down... :-)

[Ruhi Arslan]

Won't be required if he uses cast-iron-sanding-sealer, either that or use a hand plane to shave it down... :-)
I would make sure sure to use planes purchased from HF not from LV, they all come from the same factories anyway... :D

[Chris Rosenberger]

Chris,

Did you have the same problem when jointing as I before you sanded the table. What was your procedure? I'm still waiting for Larry to respond but I'm interested in what you said you did to solve this problem

My problem was the same as yours. The ends of the tables were high. I used a Festool RO 150 sander with a hard pad. I started with 150 grit discs & worked up to micron discs. I kept the sander moving & checked it with a straight edge often. I thought it worked but since the experts here said it could not be done, maybe I dreamed it.

["Patrick G Rainsberger"]

I started this post back in 2011. I became quite frustrated with the answers I was getting. I pretty much disappeared from Sawmill Creek. There were too many people chiming in that didn't contribute anything to the conversation. I view this website as a conversation, not a lecture room. I feel I need to tell you what I did to solve this problem.
I started off using the RO sander with 100 grit. It didn't touch the problem. I went down to a 60 grit and it still didn't do anything. I ended up using a belt sander with 60 grit sandpaper. I must have used 20 belts to finally get the surface flat. It took me at least 2 days to accomplish this. I put a few dents in the surface when the belt sander slipped, but they don't affect anything. The surface has been flat and I've had no problems.

[Doug Herzberg]

I started this post back in 2011. I became quite frustrated with the answers I was getting. I pretty much disappeared from Sawmill Creek. There were too many people chiming in that didn't contribute anything to the conversation. I view this website as a conversation, not a lecture room. I feel I need to tell you what I did to solve this problem.
I started off using the RO sander with 100 grit. It didn't touch the problem. I went down to a 60 grit and it still didn't do anything. I ended up using a belt sander with 60 grit sandpaper. I must have used 20 belts to finally get the surface flat. It took me at least 2 days to accomplish this. I put a few dents in the surface when the belt sander slipped, but they don't affect anything. The surface has been flat and I've had no problems.

Patrick, I saw your post for the first time today. I'm glad you came back to give the rest of the story. I'm restoring an old jointer and am more interested in getting the surface rust off than anything else at this point, but I have thought about how I'm going to get the tables flat if I need to and the information in your thread was helpful.

[Steve Wilde]

Old thread but this is probably as good as any place to ask. I have a DJ20 that I need to adjust the beds to coplanar. I have the instructions on how to do it, but I can't find a spanner wrench anywhere to adjust them. Anyone know of a good source? I checked online a bit and thy were all $35+. I was really hoping for a cheap wrench since I hopefully won't ever be doing it again once it's set.... Thanks

[Al Launier]

This also is the first time I've seen this thread. When I read the OP's initial post what immediately came to mind was that the infeed & outfeed tables were perhaps out of alignment. Reading further I noted that others thought he same, plus there were a number of other proposed solutions.

I can certainly say I had my problems when I purchased my jointer as I couldn't get the jointer to mill a flat surface that was parallel to the top surface. Now before anyone jumps the gun and states that a jointer is not supposed to mill parallel surfaces I must say I already know that. In my case I tried jointing boards that had been run through the planer and the result was boards coming off the jointer that were like clapboards, tapered from one side to the other. I thought I was using the wrong technique, even after Glenn Bradley took pity on me and sent me a homemade video of him showing me the correct procedure for feed a board through a jointer. Still didn't work. I even had a local woodworking friend who was very knowledgeable and very experienced try my jointer to no avail. What to do?

I subsequently ran across a recommendation for a comprehensive book entitled "CARE and REPAIR of SHOP MACHINES", A Complete Guide to Setup, Troubleshooting, and Maintenance authored by JOHN WHITE. Let me say this is an extremely detailed and well written book with clearly stated procedures for maintaining shop machine tools. I followed the procedure detailed by John White and damn if that didn't completely take care of the jointer problem. The tables were not co-planar and required shimming to correct – a relatively easy fix. I can now enjoy jointing wood with complete confidence.

So, I would strongly recommend that anyone involved with equipment used in woodworking consider buying this book. It is everything it claims to be. It sells for only $19.95 and is a wealth of information for Table Saws, Jointers, Thickness Planers, Drill Presses, Router Tables, Miter Saws, and maintenance of other equipment. Please know that I have no affiliations with this author, or anyone connected to him or his retail sales other than being a one-time purchaser of this large book with many illustrated photos. This would make a wonderful Christmas Present.

[Bob Grier]

Steve, I had the same problem. I gave up after a couple hours looking for the wrench and tried gripping the little bit of round stud sticking out. I didn't want to do this because of potential scuffing of the stud but it turned out that the studs turned very easily (after set screws were backed off) and I was able to adjust the beds with no problem. You might try something like this, maybe even use a piece of rubber between the jaws to avoid scratching the adjusting studs/rods. If they don't turn easily, then nothing lost.

[Steve Wilde]

Bob,
Thanks, I'll give it a try!

[Pat Barry]

I started this post back in 2011. I became quite frustrated with the answers I was getting. I pretty much disappeared from Sawmill Creek. There were too many people chiming in that didn't contribute anything to the conversation. I view this website as a conversation, not a lecture room. I feel I need to tell you what I did to solve this problem.
I started off using the RO sander with 100 grit. It didn't touch the problem. I went down to a 60 grit and it still didn't do anything. I ended up using a belt sander with 60 grit sandpaper. I must have used 20 belts to finally get the surface flat. It took me at least 2 days to accomplish this. I put a few dents in the surface when the belt sander slipped, but they don't affect anything. The surface has been flat and I've had no problems.
Thanks for the update. Why did you wait 4 years to try it? Or, why wait 4 years to tell us??