Had A Tablesaw Top Refinished Today

[Eric P]

and wow what a way to make a machine look/feel like NEW. Bought a used Powermatic 66 last Fall (love the saw!) and after close inspection noticed the top bowed down slightly, about a 40 thousandths dip, probably due to abuse. Not a big deal but it meant I had to re-sqaure the blade for different width boards. I almost faired the top with an epoxy grahpite mixture but ran across a Blanchard grinder a couple hours away. Called the guy and he said "hey Powermatic makes their tops near you, take it to them". Well I'll be, the very shop where they grind and machine them is less than

90 minutes from me. Took it to them and they said it could be re-worked. Picked it up today and it's like a mirror and FLAT FLAT FLAT! Also got to take a tour of where the tops are made. It's one helluva operation and nice to know one of the things that Powermatic has done so well for so long has managed to stay home and not turn chiwanese. Powermatic will get my business again.

-- Eric P

[Unisaw A100]

I'm curious as to what abuse would cause the top to bow?

Also, what was the final cost?

UA100

[Eric P]

UA100

Perhaps another piece of machinery or some lumber fell on it, or someone stacked it with something heavy. Tablesaw tops may seem like armor when in truth they need to be handled with care. The bow was worse on the infeed edge and gradually went away by back of the table. I thought the top may have moved on its own over time but according to the Powermatic guys that rarely happened back when my saw was built (late 80's) since they still aged the tops.

Cost was $105.

Eric P

[David F. Eisan]

Dear Eric,

Any photo's of the plant or before and after photos of the top?

David.

[Eric P]

David

Sorry, no pics. Had I known I was getting a tour I'd have brought the digital. DOH!

-- Eric P

[Larry Jaques]

On Fri, 23 Apr 2004 23:54:22 -0500, "Eric P" brought forth from the murky depths:

I'm curious what they charged for the grinding.

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[Mike Reed]

Profit? It's a business, and the saw was out of warranty. Ford would charge to straighen the frame on a 1985 car...

-Mike

[Mike Reed]

Dang, sorry for my other post, I read your question as "why" they charged for the grinding.

My bad.

[Larry Jaques]

On 24 Apr 2004 13:12:30 -0700, [e-mail] (Mike Reed) brought forth from the murky depths:

I said "what", not why, Mikey. Let me rephrase that as a question for you. I'll type real slowly + mouth the words so you catch it this time, too:

"How much did Powermatic charge to grind the top?"

(Sorry, low tolerance today.)

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[Larry Jaques]

On 24 Apr 2004 15:00:24 -0700, [e-mail] (Mike Reed) brought forth from the murky depths:

Too late. I had already replied. ;)

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[William]

How did they deal with the depth of the miter gauge slots, or did they at all ? I assume that your 66 has the same "T" slots as my 72 has. I have been thinking about running my top through my wide belt sander, as it is equiped with a contact roller soft enough for use on metal.

William.....

[Unisaw A100]

Lately I've been pondering the uselessness of miter gages. For cross cutting a sled is a way better way to go. For angles a miter saw can't be beat. Yes there are those instances where a gage is useful but I find myself trying to get around it.

Oh, all you have to do is have the bar on your favorite gage skimmed down a couple of thou.

UA100

[Eric P]

William

Luckily the amount of material needed to be ground off to get her flat again wasn't so much as to adversely effect the miter slots. In fact the first thing the guy said when I saw the top was the miter slots were at the very lowest end of spec, but still within spec nonetheless. I dropped my miter gauge in and sure enough it's a hair below the top. If the miter slots had ended up too shallow I'd be in the market for a new top. I read UA100's comments and see how some may not be all that concerned if the slots are too shallow but I use several miter gauges and would hate to grind them down and know that everytime I bought a new device that uses the miters slots that it would have to be modified right out of the box. Keeping things in spec seems like an easier way to get by.

Eric P

[William]

Do you have any way to measure the depth of your slots ( as you stated that they are at or close to the limit ) that may tell me how far I can cut the top of mine down ( as I don't have the miter gauge at this time:-) I could machine off some material off the gauge bar but like I would rather not. Did you see how they set up the tops for the machine work? do they shim them to level on the mag chuck ( I assume that they are blanchard ground?) ?

Thanks

William....

[vmtw]

Did you take the top in, or the whole saw? The reason I am asking is that I have heard that you can distort the top of a saw by the way it is bolted to a cabinet. Just curious. Scott

[Holly Gates]

I got a PM66 from '72 or '73 last summer and it had a giant hump in the middle of the table right over where the arbor pulley sits. It was about .060 tall. On the bottom you could tell that the pulley had at some point been rubbing on the table; maybe the resulting heat contributed to the hump. Anyway, I took it to a blanchard grinder in Chelmsford, MA and they ground it plus the one wing I have for 110 dollars.

Not sure how the mitre slot situation is since I don't yet have a mitre gauge. I'll let you know when I get one whether it is a problem. I figured I could just live with sleds or make a custom bar if the slots ended up getting too shallow.

I've got some pictures I'll post at some point of the blanchard grinding operation; it was pretty cool.

-Holly

[Eric P]

Scott

I took the top in three pieces. Not sure if I could bend it out of shape just by bolting it on unless something was trapped between the the top and the cabinet.

-- Eric P

[Eric P]

William

The slots are right at 3/8" deep.

-- Eric P

[Phillip Hallam-Baker]

EEK! NO!

Your wide belt sander is at best going to provide you with a perfectly straight edge in one plane, and that only if you had a perfectly straight drum (not a chance).

Imagine for a moment you had a table that was a cylinder section, and the sander drum was a perfect cylinder, it would go in the sander fine, but it would not come out flat.

In practice you are not even going to do that well, your sander is probably way more out of whack than the worst table saw top you could imagine. If you looked at the drum on a scale of thousandths it is going to look like a wobbly potters vase - and that before you put the paper onto it.

The only way to get a flat surface is to use a tool that is designed to create a surface flatter than its own tolerances - like blanchard grinding. At a reported $100 that is a great deal to fix a $2000++ machine (I know you can buy a Unisaw for $1800, possibly less if you go second hand, but add in set up time...).

Question is whether I could take the flat but not mirror polished top of my unisaw and get it machined to the ludicrous mirror finish of the powermatic. I don't imagine for a minute that this would improve the working of the machine, but that mirror finish sure looks really cool.

[bridger]

cast iron will flex more than you probably think. if the cabinet rim and the mounting bosses of the saw table aren't in the same plane, the top will probably be the one that gives.