Hollowed jointer infeed table

[ian maybury]

Checking the cast iron infeed table on my 16in planer thicknesser it's coming up about .004in low in the centre of the end/edge of the table parallel to the cutter. (the set up guide suggests the tolerance is .002in) The hollow/dip extends for the width of the table, but gradually reduces so that by the time the two sides are reached it's gone. It extends up the length of the table for about 25% of its length (perhaps 8in), reducing all the way so that by then it's gone. It's very flat over the rest of the surface, well within spec. The outfeed table is flat, seemingly within .002 all over.

I've never checked a table before, and consequently don't have much to compare it to. Has anybody got any idea how much of an issue this is likely to be in terms of jointing performance?

I'm tempted to try the clear lacquer filling method discussed here before as a possible fix for this sort of thing. Has anybody done this, and if so how did it turn out? Looks, wear etc

Thanks

ian

[Chris Fournier]

Checking the cast iron infeed table on my 16in planer thicknesser it's coming up about .004in low in the centre of the end/edge of the table parallel to the cutter. (the set up guide suggests the tolerance is .002in) The hollow/dip extends for the width of the table, but gradually reduces so that by the time the two sides are reached it's gone. It extends up the length of the table for about 25% of its length (perhaps 8in), reducing all the way so that by then it's gone. It's very flat over the rest of the surface, well within spec. The outfeed table is flat, seemingly within .002 all over.

I've never checked a table before, and consequently don't have much to compare it to. Has anybody got any idea how much of an issue this is likely to be in terms of jointing performance?

I'm tempted to try the clear lacquer filling method discussed here before as a possible fix for this sort of thing. Has anybody done this, and if so how did it turn out? Looks, wear etc

Thanks

ian

You don't say what you are using as a reference tool Ian. I'd joint the edge of a couple boards and mock up a glue joint. If it's tidy you're good - assuming decent technique of course. I think that you're going a bit overboard on the scrutiny, look at the machines output and you'll have a real world answer to your question.

[John TenEyck]

I'm confused if you are talking about a jointer or planer, but I would think that if it's 16" wide it must be a planer, yes? Anyway, if it's really a jointer, I wouldn't worry about it as long as the outfeed table is flat. If it is a planer, however, I had the same problem with my well used Foley-Belsaw when I got it. I couldn't figure out why boards I put in that were jointed dead flat came out with a crown in the center until I finally checked the planer bed. It was out a lot, more like double what you found. I thought about taking the machine apart to get the bed reground, but decided to try to "flatten" it first. I put Bondo on it, and doctor bladed it as flat as I could before it set up. After it cured, I sanded it flat with sandpaper glued to a flat block of wood. When I was satisfied it was flat, I glued a piece of Formica to it to give a durable, low friction surface. It's now flat as close as I can measure it, certainly within +/- 0.002". That was about 4 years and a couple 1000 BF of lumber ago.

John

[David Kumm]

Hi Ian, welcome to the world of grinding tolerences. Even the Euro stuff isn't speck'd real close anymore. Your situation is about as good as life gets though as it shouldn't affect much. Your hand feed pressure is back on the flat part of the infeed and by the time you get to the last 8" or so the pressure is on the outfeed side. You are out of whack in the best possible place- and so is your machine. Dave

[ian maybury]

Ta guys. It's a Hammer A3 410 planer/thicknesser John, and the issue (such as it is, it's actually well within Felder's spec) is on the 'jointer' infeed table - in the area just before the cutters.

Pardon my getting a little 'engineering' about some of this stuff Chris. I've been checking with a ground steel straight edge and feeler gauges - although on some of the longer measurements it was necessary to switch to using a good quality level as it wasn't long enough. Realistically the issue isn't that I'm kicking up about a problem, the motivation is more to gain an understanding of how the numbers relate to actual performance - with a view to sorting out anything needing doing up front. I used my last machine for over ten years, and haven't got a clue as to how flat or otherwise the tables were. :)

I'm in set up mode right now. What caught my attention is that the tables on higher end machines are toleranced to be within about 0.002in flatness - quite a bit better than your usual hobby model. Luckily the outfeed table is very close to flat, less than about 0.002in.

For sure it's not going to matter a lot on longer pieces David, and on shorter pieces whatever curve it might induce isn't going to matter a lot either.

One of the guys on FOG has just responded by posting a photo of his hand scraped tables on a similar machine, it's seemingly not too labour intensive or expensive - although there's some technique involved. Might be worth a try if it turns out that the the risk/input/return mix makes sense...

ian

[Chris Fournier]

I would worry most about my outfeed table while jointing and yours is flat. As long as it's parallel with the cutter head and to my liking about .004" lower then you are golden. Once your board passes over the cutter the operator should be pressing the board on the outfeed table.

I cannot remember the name of the technique but once upon a time I was in your shoes and I made three 5' long boards and placed three machine screws in the edges of each board in the same spot. Using the three boards and touching the screws off against each other you can get one board that is perfectly straight. I used this shop made, highly accurate straight edge to check out my jointer back in the day. I know that my boards did not come out any straighter or flatter for the exercise but I was in your mode of "gotta know". You could try this technique to get to the "n'th degree.

[Richard Coers]

The result of your work on a jointer is based on the outfeed table. The infeed is just there to hold up the wood and set the amount removed. Proper technique on the jointer is to move all hand pressure to the outfeed table as soon as possible, and not have any pressure, or return to the infeed table at all. The cutter head is finely set to the outfeed, not the infeed. It's the same as when someone puts a power feeder on the jointer. It's mounted on the outfeed. You are well within tolerance for a infeed.

[Jeff Duncan]

As mentioned the important thing on a jointer is that your wood come out flat and straight. If you can get flat straight edges, everything else is futile. If you cannot get straight flat edges, then you find the problem and address it.

As for hand scraping the tables.....I've never heard anyone describe it as "not too labor intensive"! There's some good posts about it on OWWM, and although it looks cool it is not something I would want to try without having a LOT of free time on my hands. It's something you would do to get a very precise surface and takes a LOT of patience. If you try it be sure to post some pics for the rest of us though:)

good luck,
JeffD

[Mel Fulks]

yeah. Get the table adjustment right and there probably won't be any problem. Understand that a knick in the knives is actually more of a factor than the small deviation you have described .Scraping machine tables is mostly now for large, worn surfaces on good machines that are too large to send out for rebuild. It was also a job in a machine factory in the final set up and adjustment department . If they still did that your jointer would be perfect. Oh, in the cases where scraping is done , they bring in a traveling expert. If you are interested in learning it you can but its like anything else, without regular use, it is difficult to maintain skill.

[ian maybury]

One of the guys on FOG posted this in response to my raising the question on FOG Jeff (and subsequent to my putting it up here) - he reckoned about five hours: http://groups.yahoo.com/group/felder-woodworking/photos/album/150670118/pic/1566883813/view He wasn't pushing it as a solution for everybody (it's a highly skilled technique, is hard work and not for everybody), and that time's not very likely for a beginner - but on the other hand IF it makes sense to rework the table scraping it in situ might make sense versus stripping the tables off, driving (in my case 120miles each way) to a grinder, paying for the work, risking that the grinder would make it worse, then driving home and reassembling the machine.

He opened my eyes though to the practicality of scraping as a technique for sorting out this sort of thing. Here's a Japanese gent in action: http://www.youtube.com/watch?v=JGYwJ3RQpQo&feature=related


This guy in the US offers an instructional video plus sales of tools for hand scraping:

http://www.machinerepair.com/Home.html
http://www.machinerepair.com/Tools.html
http://www.andersonscraper.com/Anderson-Hand-Scrapers.php



This sort of debate inevitably comes down to arm wrestling between those on the 'it doesn't matter' side, and those less sure. My sense is that it's probably a case of 'it depends' on the type of work.

Yes, it's flatness of the outfeed table that matters most. Not to mention that when jointing a long workpiece a 0.005in dip in the last 150mm of the infeed table isn't going to matter a lot. Provided that is that the rest of the infeed table is flat and correctly aligned. On the other hand it has to matter on a shorter piece - although ensuring that it's kept flat on the outfeed and doesn't rock back must help too.

It has to matter if the aim is to remove a consistent very thin skim from a short piece without knocking the sides out of parallel. I'm guessing that the makers of the better quality machines don't seek to hold 0.002in flatness for nothing. Think too of how obvious tiny out of flatness can be when using a hand plane, or paring with a chisel.

The plan is to run the machine for a while and see how it all shakes out...

ian

[Mel Fulks]

On a short board how much error do you think could accumulate ? Five hours for him or for you? If its five hours of his time what will it cost? The castings of your machine were probably not aged before machining so the table could possibly move some after you fix it. If you have the type of table adj that is a stick ,instead of a wheel, adj is much more difficult but can be done. Your work does matter, whether the error in the machine matters can not be known without accurate adj. I have seen guys ruin the fine factory adj. because they did not know that a knicked knife mattered! If you can't get the adj right with the two four foot boards touching along entire length determine whether the problem is imprecise adj, mechanism, or what. I once called about an old jointer with the drop down end out feed feature. The owner told me he had gotten the out feed table machined because the end of the table was 30 thousandth too low! He obviously did not understand the machine adjustments.

[ian maybury]

Fair comment Mel, but there's no problem at the moment. Only a discussion on the possibility of flattening tables, and the risk/input/benefit calculation associated with the various possible methods...

As ever in these things it's good to know that while it is a highly skilled and labour intensive procedure that scraping is an option...

ian

[Jeff Duncan]

I'm not trying to take a side as that doesn't help anyone. In my opinion "what matters most" is getting straight and flat stock. If you are, then your fine, if your not.....then your not. Sometimes guys overcomplicate simple things;)

Run some wood through your jointer and see what happens. THEN decide what, if anything, you need to do. I read so many posts on these forums about guys going over every square inch of cast iron with all sorts of precision machinists tools trying to see where they need to "fix" something. Instead of doing the simplest thing, running a piece of wood through and evaluating the results. If your work is coming out straight, then spending 5 hours fixing a problem that isn't there is wasting 5 hours. If your wood is not coming out straight, then you can track down the issue and spend time correcting it.

FWIW I'm not afraid of spending time on equipment either. I spent almost 2 days aligning my 16" jointer when I bought it! It was a strange Italian parallelogram design that required drilling and tapping the eccentric bushings in order to re-align it. It was not fun, but I got the close to 8' of table lengths to within .004 which was good enough for me:D

good luck,
JeffD

[Mel Fulks]

What ever you do is fine. We just want you to be happy...(heard that somewhere) Good Luck!

[Kirk Poore]

Ian:

Any board you face joint will move slightly after the jointing is done simply from relieved stress, let alone any changes in moisture. Since your dip will only come into play on wider boards (say, 8" +), I'd expect that movement to be more than the dip in your table (which is <1/128" or about 1/8 of a mm). And you're then going to run the board through the planer to get the final thickness & flatness anyway. I'm with Jeff--try it, you'll like it as it is.

Kirk

[ian maybury]

:) Don't worry guys, in principle pretty much everything said is spot on. There's no gain for anybody in heading off on a hare brained and OTT set up jag. Against that if a machine isn't right my personal inclination is to put the time in to sort it out rather than live with an ongoing problem. The mythical 5 hrs (+?) is nothing compared to ongoing irritation in my mind - if that is it turns out that there is a real problem.

There is a problem with the A3 (but it's unlikely to be caused any of the above) - it's getting a close looking at because when I first ran it on hardwood a few weeks ago (beyond a very quick fire up after delivery about a year ago) it clearly wasn't right. Inclined to chatter/hammer the piece. The Hammer K3 panel saw was similar - it performs beautifully now, but it was miles off on set up as delivered.

Next step is to set it up to the manual and see how it does. If there's still issues then it becomes a case of step by step working the bugs out as far as is possible...

ian

[Mel Fulks]

Since you don't mind working through these things you are a good candidate for fine vintage machinery; at some point.

[ian maybury]

It's a kind of a lesser of two evils deal in my mind Mel. It'd be nice to have had the Hammer machines delivered perfectly set up, but realistically (a) even if i had requested (and paid for) set up they probably wouldn't have been as required, and (b) working through a machine is realistically the only way to learn it. I ran a Robland combo as it came for many years on DIY work, and never summoned the application (never really found the need because the work wasn't too precise) to get stuck into learning it properly. The aim right now is to step it up a few levels, and I can think of no other way to figure out what a machine can do short of a lot of painful trial and error.

The good news on the Hammer machines is that while the set up coming from the factory has been very hit and miss, in general the parts are good - so that by and large they are capable of being set up pretty accurately. e.g. tables etc while not perfect are pretty flat and so on.

One issue that does arise is that this sort of approach brings you head on into collision with commercial reality and its practical consequences. In that Hammer while very decent machines at their price point are not Felder's top of the line brand, and as such this has consequences. e.g. slightly wider tolerances, lighter and less sophisticated constructions, and less by way of adjustment mechanisms. You could say in a sense that an exercise like this is about (through extra work and effort) persuading machines which were at the top of a given budget range to punch above their weight.

It's all good fun (and as an engineer I'm as happy working on a machine as when woodworking), but given a lottery win and it'd be Format 4 stuff or something else high end in engineering terms all the way....

ian

[Chris Fournier]

You are correct that scraping would allow you to clean up your infeed table but this technique requires some expensive (or laboriously crafted tooling) ans a prcactised skill set. It's not for newbies especially on your machine. Check out Home Shop Machinist back issues or their forum for more info on the technique if you're interested.

Granted my SCM machine was top of the line but the set up was spot on with the exception of the accessories. I was super impressed by the accuracy of the set up and the clever features on the machine that allow you to adjust it into and far out of perfection!

One thing to remember on the sliding saw is that the material when on the slider is actually not resting on the table surface around the blade. The slider is above the table surface, this can allow flutter/movement of the piece being cut that you wouldn't get on a cabinet saw.

[ian maybury]

Good for SCM Chris. No question but that scraping is a definite skill set. I posted a video and some links to a guy offering tools earlier in the thread. It'd be a learning curve, but I'll give it a go if it proves to be truly needed as I've generally found that I can pull stuff like that off. I'd rather trust my own capabilities than hand a table to a guy with a Blanchard grinder I've never seen before and know nothing about - it can be a little different here in Ireland.....

ian

[Jeff Duncan]

The aim right now is to step it up a few levels, and I can think of no other way to figure out what a machine can do short of a lot of painful trial and error.

ian

If your talking about learning the woodworking aspect of using machinery I would recommend taking some classes over trial and error. There are so many ways to do different things that have already been learned over generations, you can spend more time making things instead of learning how to make them;) There is so much stuff I learned the hard way, I really regret not staying longer at my previous job and learning more from the experienced guys. Learn as much as you can through others....everything else is beating your head against the wall and it starts to hurt after a while:o

If your talking about learning how the machines work....than yes, getting your hands dirty is good experience:D However certain machines are much easier in general than others. Jointers, shapers, and table saws are pretty easy overall, and do require an initial setup to get proper use. Planers on the other hand can be quite complicated and should be ready to go from the factory. I dread the day I have to do any serious work on my planer as it is not going to be fun:(

good luck,
JeffD