My PM-66 main table top and wings are out of flat by about 1/32″ to 1/16″. Hasn’t bothered me to date (saw is 5 years old, purchased new), but I just discovered the right mitre slot is a few thousands of an inch narrower than the left. My new Incra mitre guage is calibrated to fit the left slot nice and snug with no slop. Put it into the right slot, and it’s too tight to slide freely.
Have considered using 400 grit sandpaper to carefully widen the right slot to match the left, but am wary of this method. I could probably do this without throwing off the alignment, but would rather be safe than sorry.
Which raises the question, should I just take the main table and wings to a machine shop and have them resurfaced dead flat? They could also widen the right mitre slot at the same time.
Anyone ever done this? How did it turn out? The top and wings are thick enough that I’m confident there is plenty of metal to prevent the grinding process from making it too thin. They are about 1/4″ thick. Any ideas on cost?
Regards,
John
Replies
contact Powermatic. I've heard they "season" their castings to avoid this problem. I have a 1997 #66 that had a bad arbor and they sent me the new one piece arbor for free.
This issue seems to come up quite frequently, and is, in my opinion, the most bass-ackwards way to deal with an uneven top. Set aside all the issues involved in re-grinding a top, and let me first ask where anyone gets the idea that a "machine shop" will do a better job, (dead flat?) than the grinding process done at the factory. Unless the top is supported correctly during grinding, it will be no better than what you started with it.
I'm not 100% familiar with PM 66's, but, if anything similiar to a Unisaw, where the top is bolted down to the steel cabinet, you may be able to correct or minimize any distortion by using shim stock at those points. For the miter groove, unfortunate that one is thinner than the other, but, I'd wager a guess they're both probably within specs. You can get a file specific to this application (forget what they're called, exactly) that's smooth on the edges, but with the usual cut, (you'd want a fine mill cut) on the faces.
Just my opinion,
GC
A waste of time and money in my opinion and experience. I've had many jointer tables ground over the years from a $100 to $200 per table. Obviously a 16" jointer is bigger. You can't just bring it to any machine shop. Most don't have grinders that big and if it says ISO 9000 on the sign outside the cost goes up dramatically. Extra expenses to meet the higher set standards of the industry. I've got hundreds of machine shops in my area but only one that can handle large grinding. It has a blanchard grinder which leaves a circular finish like what you find on a unisaw table. A straight grind is called a precision grind and is harder to find one that can do a larger surface. When measuring the flatness don't measure the wings at the same time. My PM 66 table was slightly dipped but within PM specs. I also have a brass shims tock kit that I used to shim the wings into relative flatness which is what I suggest you do as well. Available from http://www.use-enco.com or http://www.mcmaster.com and your local industrial supplier. Regrinding the top could be risky as you will affect your miter gauge slot depth. The biggest expense of grinding is the fixturing to hold the piece. You can't just plunk it down on the magnet as the magnet is strong enough to distort the top. Metal can move like wood in a way. I had one jointer table that had to be ground twice. Sometimes taking a little off the surface releases stresses inside the metal. This was an Oliver jointer that was made in the 50's. This question came up a short time ago and the person asking the question contacted PM and they advised against it so I suggest you call them to get it straight from them. Since they already are set up to do the set up it makes sense to get their opinion. They don't grind the wings attached to the top. 400 sandpaper is too fine. I'd use a file to file off the few thousandths in the miter slot. That and investing in a pack of shims for the wings you should be well within tolerance for the least amount of money and aggravation. Asking the cost of grinding on a woodworking forum is a waste. Not many here have that kind of work done. A metal working forum would be more appropriate and it can vary by hundreds of dollars. I just had a 12" moulder cutter head dynamically rebalanced because our grinder trainee slipped and ground into the face of the cutterhead. I got prices from four different shops from $150 to $500. A new head costs $600.
I agree with Rick. If the table and the wings are each flat and are just misaligned, shims under the bolts is the way to go. Also agree about widening the miter gauge slot. Yes, 400 grit will do the job, but it will take a long, long time. Filing it is not a big risk if you stop and check your work occasionally.
Another alternative, if you have more time than good sense, :) is to get the book Machine Tool Reconditioning and learn how to scrape cast iron. Flatness to within microns is possible with careful hand scraping and the right measuring tools. If you're interested, and if your library doesn't have a copy, see if you can get it through interlibrary loan before you rush out and buy one. The retail price is somewhere around $95.
Pack of shim stock $30...good advice priceless. Personally I think scaping a table is overkill for a tablesaw. It's a lot of work and time to master.
I agree. You'd have to pretty much want to acquire the skill for its own sake.
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