How To Flatten A 12" Jointer Table?

[Derek Arita]

I have a 12" Mini Max jointer/planer that has a top that is not as flat as I'd like. In places it's out .010. Anyways, it seems like a big job to flatten the top, as I've never had to have it done on any other machine I have. I/ve heard that I can take the machine to a machine shop and have it done.
How do I find a good machine shop that can do it? Do I remove both tables and take them in? How do they flatten the top? By the way, I'm in the Sacramento, CA area.

[Brian Brightwell]

A surface grinder is the tool of choice. It would take a good size grinder.

As a side note. The throat plate on my Laguna table saw was warped. My first thought was a machine shop with a surface grinder. But then I put it on a backing board and ran it through my wide belt sander. An ink marker on the surface indicated the progress. I made very light passes and it took awhile but a lot less time than taking it to a machine shop. By the way the throat plate on a Laguna is rather large,

[Ellery Becnel]

Derec, is the .010 dip across both tables or is it in just one table? Is it a dip in the middle, or low on one end? If it is low on one end it might be possible to shim the mounting portion to adjust? If it is a dip, then it would have to be disassembled. They will charge you more than you can imagine. It would have to be surface ground. Normally the machine has a magnetic table to hold plates that need to be parallel within .0001. Some have a vise that can hold iregular shapes. There is a large precision grinding wheel that is above the part. The table strokes from left to right and front to back with the part. The spindle with the grinding wheel moves downward in .0001 increments. The table is flooded with coolant so the wheel and part does not get overheated and explode. It will probabbly need to be an industrial machine shop. This is not a cheap job to do. If a smaller shop can do it than you might save some money. If you know any machinist in the area, you might want to talk to them for local help. I hope this helps. If it can be adjusted it will be better for you.
Good luck Ellery Becnel

[Dan Forman]

I have a 14" MM J/P who's table is not as flat as I would like either, but have managed to adjust it so that it really doesn't seem to matter. With mine, it's mostly dips, the most significant ones are right behind the the steel lips on either side of the cutter head. I can't use the two drafting triangle method for adjusting the tables to parallel because the dip will throw the triangles off, but a 4 foot machinist's straightedge gets me in the ballpark, then fine tuning by placing two jointed edges against each other will reveal if there is any convexity or concavity present. Be sure to use a piece that is wide enough that it won't curve on it's own. I found mine produced a convex edge, so that the two edges rocked ever so slightly. Removing a .001" shim on the outfeed side fixed the problem.

Seems that for that kind of money you should get better tolerances, but with a machine so big and heavy, unless it's really out enough to cause measurable problems in your work, you're kind of stuck - especially if it's in your basement! I think a hump would be more problematic than a dip, as it would force the workpiece up, whereas the contour of a dip might be bridged if not using too much force.

Dan

[ian maybury]

Much as the guys have said - it's not the easiest issue to find a solution to.

I've been looking locally for an option to get the tables ground on my 16in planer thicknesser which has similar issues - which in my case won't seem to easily dial out without dropping tables out of plane. (it wants to cut slightly convex)

The issues i've run into reflect what the guys said. It isn't exactly a happy hunting ground for machine shops over here, and it's not that easy to find a large enough surface grinder. The other issue is that most use the aforementioned magnetic chucks, and with these it's really important to ensure that the table is very accurately supported and shimmed so that when the magnet is switched on the table doesn't deflect. This is basically a labour intensive (= potentially expensive) deal, and the risk I couldn't find a way past was that even that is no guarantee that it would be done properly - that the result wouldn't be worse than before. It's pretty clear too judging from the nature of the inaccuracies that my (milled) tables were not well enough supported and/or the feed rates were too aggressive when they were originally machined.

So it's very feasible, but has to be done right. Here's a couple of relevant pages from vintage machinery.org: http://wiki.vintagemachinery.org/Joi...eGrinding.ashx http://wiki.vintagemachinery.org/Fla...0Surfaces.ashx

I've taken another tack, in that I've committed to try to scrape mine flat - encouraged (with a warning that its a skilled operation) by one of the guys on the FOG site. Labour intensive and quite hard work too - and there's scope to screw up good and proper. Be that as it may i've bought a carbide scraping tool in the UK made by Sandvik http://www.greenwood-tools.co.uk/shopscr63.html , and used it as an excuse to invest in one of the very reasonably priced Chinese made granite surface plates now around which I want for sharpening and other tool set up jobs. (shipping these is more expensive than buying them)

Some scraping information links: http://en.wikipedia.org/wiki/Hand_scraper http://www.machinerepair.com/Orders.html http://www.andersonscraper.com/Ander...ular%20Scraper http://www.machinerepair.com/Tools.html There's quite a few scraping videos on Google, these give a look at the basic method of using a marking dye and a surface plate to identify the high areas: http://www.youtube.com/watch?v=JGYwJ3RQpQo http://www.youtube.com/watch?v=y2AUew5Evxc

I can't say how it's going to work out, but it's the big job for the holiday period. Wish me luck...

ian

[Phil Thien]

.010" is a lot. That is 1/10", almost 1/8". How are you measuring that?

Are you sure it is that far off? If it were that far off, I'd think you'd be able to see it by just looking at it, or running your hand over it.

[Jerry Wright]

One hundreth of an inch is not much in the world of wood seasonal or daily movement. Why the concern? That is an honest question- I don't understand the problem.

[David Kumm]

.010" is a lot. That is 1/10", almost 1/8". How are you measuring that?

Are you sure it is that far off? If it were that far off, I'd think you'd be able to see it by just looking at it, or running your hand over it.

.010 = 1/100. If the infeed is off it is much less of a problem than the outfeed. Dave

[johnny means]

Is this issue affecting your ability to joint a board? We tend to waste a lot of time and money chasing theoretical tolerances when close enough will do. IMO, Pi is 3.14.

[Brian Weick]

Blanchard Surfacing........


Talk to a machinist with a horizontal blanch grinder.



B,

[Phil Thien]

.010 = 1/100. If the infeed is off it is much less of a problem than the outfeed. Dave

LOL, thank you. What a brain-fart.

[Jeff Miller]

Total junk......unfixable I'll give ya a $100.00 for it

[Chris Fournier]

0.010" most likely isn't going to ruin your life and I would certainly want to know that my measuring tools and methods were extremely accurate. Where this 0.10" deviation exists is important. A surface grinder is not what you are after, a Blanchard grinder is the tool that would be used to remedy your table. Expect to spend some money as the set up is critical and flat is only one measurement that matters and quite frankly it is not the most important criteria; if the table comes out flat but not "square in relation to the cutter head you are in a far worse place. If you get good results from the machine I'd leave well enough alone.

[Brian Weick]

For all the money your going to spend for such a small diffrence,,,and when it's done, you won't know the difference....you may want to think twice about this.

Metal milling machines....lathes, stroke planners,vertical milling machines.......something of that nature I can see needing to get back up to specs, but wood machines ........most if not all are slightly a skewed in some way.......


I wouldn't have it done......

JMPOV,....

B,

[Sam Puhalovich]

Hello, everybody ... after 'lurking' on SMC for about 10 years ... I think that I can finally make meaningful 'pay-back' for all the information that's helped me.
I started into wood-working as I was preparing to retire 12 years ago ... I'm 74 now and still consider myself pretty-much a 'newbie' with every project being a another learning experience.
Whenever a project is finished: it seldom makes any difference what the exact size turns-out to be. However; everything is easier when the pieces are flat, square and parallel.
Having a machining background ... I don't want my equipment introducing a machined-in fault that will introduce 'difficulty' to any of the subsequent the joinery.
Last year I bought a Robland X-31 that had been sitting in various storage facilities for about 10 years. The cast iron tables stress-relieved as they aged and went out-of-flat.
I took the 12" wide tables to a shop that does car engine re-builds. They have a head-flattening machine that netted virtually dead-flat tables ... by any means that I could measure.
In the past, I had seen head-flatteners that had a grinding wheel like a vertical grinder ... this one had a 14" milling cutter. Set-up for the operation was about 5 minutes with no 'exertive' clamping used that would impart any kind of flex to the table ... far-and-away simpler then anything that would need to be done for a surface grind operation. Cutting time was less then 15 minutes per pass. The cost was $50 per table.