Question about TS fence and blade alignment

[Jason Morgan]

I was reading around an saw people talking about flattening the face on their rip fence. I just measured mine and with the dial indicator set at zero at the operator end, it will wiggle between 0 and 0.004" as I run it down the length of the fence (in the stock direction). My best check of the blade to miter slot is "within the same 0.001", that is, when I mark a tooth, put the indicator against it and set to zero, the same tooth measures 0.000" at the other end (8 inches or so down the travel of the slot, I suppose I could figure out the exact length, but its been a long time since that sort of geometry was needed by me). Should I go in and try to shim this out? Most of the variations are around the 3 bolts that tie the face to the arm of the fence. Its a powermatic rip fence. Or, would I be better off getting rid of the UHMW face and making one up out of MDF or something like that? The reason that I ask is that my blades seem to "gum up" faster than I think they ought to and I notice some slight burning on most cuts.

[scott spencer]

Hi Jason - Instead of shimming the faces or replacing them, you might try a light pass on a jointer and planer to flatten them.

[lou sansone]

I am sure you know this, but the fence should drift away from the blade at the exit end by a few thousands of an inch. if is completely parallel you can be getting some extra scuffing from the blade and that might account for the pitch build up. btw what type of wood are you sawing ? cherry by any chance ? it loves to burn with too slow of a feed rate.

as far as the 4 mills wiggle, remember this is wood we are talking about

lou

[Rob Blaustein]

Hi Jason - Instead of shimming the faces or replacing them, you might try a light pass on a jointer and planer to flatten them.

I've noticed the same thing on my Grizz TS fence with its UHMW face, and in the same places--near the screws that attach the face to the fence. I thought I'd read that putting it on a jointer is not the way to go because it's very hard to joint that material as flat as it already is. You might have better luck shimming it with tape, or replacing it. I ended up replacing mine with a piece of plywood that has a nice smooth phenolic coating (got if from my local Woodcraft), in part so I could screw a steel plate to it when I want to use magnetic Grip tites. Also, I couldn't tell from your description--is the far end of the fence closer or farther from the blade? The makers of the Forrest WWII suggest keeping the far end of the fence around .005 off from parallel (away from blade) to minimize burn--I did that and it did help (also minimizes kickback).

[Jason Morgan]

Thanks for the input guys...

Lou,
Ill check the far end, but I think its close to parallel. I might try opening it up. The 0.004" is really +/- 0.002 to 0.003" Its not at the front or the back, but is sort of wavy, like Rob posted below.

Rob,
Always make me feel better when someone else has "been there and done that". I didnt want to mess it up more. Think Ill just replace it with some coated MDF or something like that.

Thanks again for the help.

[Dave Falkenstein]

I am sure you know this, but the fence should drift away from the blade at the exit end by a few thousands of an inch. if is completely parallel you can be getting some extra scuffing from the blade and that might account for the pitch build up. btw what type of wood are you sawing ? cherry by any chance ? it loves to burn with too slow of a feed rate.

as far as the 4 mills wiggle, remember this is wood we are talking about

lou

There are differing opinions about setting the rear of the fence a few thousandths away from the blade. I have tried it both ways, and see no fifference in the way the saw behaves or in the quality of the cut using a WW II blade. I have decided to make my fence dead parallel, since it will then remain dead parallel if I move the fence to the left of the blade for any reason. If the fence is set away at the back, then it will be in at the back when and if you ever move the fence to the other side of the blade.

As for flattening the fence face, I used masking tape at the low spots on my Jet Xacta fence, and got it within .001 of flat along the entire length.

[Guy Germaine]

Jason, you said..."My best check of the blade to miter slot is "within the same 0.001", that is, when I mark a tooth, put the indicator against it and set to zero, the same tooth measures 0.000" at the other end".

If you have your blade to miter slot adjusted THAT close, can you come over and tune MY saw??? I got mine to within about 0.003 when I adjusted it a few months back.

[lou sansone]

There are differing opinions about setting the rear of the fence a few thousandths away from the blade. I have tried it both ways, and see no difference in the way the saw behaves or in the quality of the cut using a WW II blade. I have decided to make my fence dead parallel, since it will then remain dead parallel if I move the fence to the left of the blade for any reason. If the fence is set away at the back, then it will be in at the back when and if you ever move the fence to the other side of the blade.

As for flattening the fence face, I used masking tape at the low spots on my Jet Xacta fence, and got it within .001 of flat along the entire length.

With all due respect Dave. I have never come across any one recommending a parallel fence to blade geometry. where have you seen this. The real danger is not being dead on parallel and having the board pinch between the blade and the fence ( if you toe out you never have this potential problem ). I am always open to learning and if you have some info on alternatives I would welcome them. I understand the rational about left of the blade setup, but I have never had a need to do that yet.
regards
Lou

[tod evans]

as far as the 4 mills wiggle, remember this is wood we are talking about

lou

amen! .02 tod

[David Fried]

... I have decided to make my fence dead parallel, since it will then remain dead parallel if I move the fence to the left of the blade for any reason.

Dave,

I had the same thought recently with my right tilt unisaw when beveling the sides of a box. I didn't want the box between the blade and fence.

I thought about moving the fence to the left of the blade but since I know I can't get the fence perfectly parallel to blade I set it out a few thou and that was end of moving the fence to the left. I ended up using my miter guage and just got the fence out of the way. As always, there are many solutions to a problem.

As for flattening the fence face, I used masking tape at the low spots on my Jet Xacta fence, and got it within .001 of flat along the entire length.

My fence has a little blade burn where the previous owner apparently touched the fence with the spinning blade. When measuring the miter slot to fence distance I noticed a little flutter in that area. I'll try your tape trick! Thanks.

Dave Fried

[Jim Becker]

One of my planned "shop projects" is to replace the UMHW fence faces with 1/2" BB ply surfaced with high pressure laminate. Mine are also "not flat". I've just never got around to it so far...

[CPeter James]

On my PM66, I have a splitter that is .005" thicker than the blade that is mounted on the stud that the original blade guard mounted on. The stud is adjustable to center the splitter on the blade. I mount the splitter (made from oak) witha wing nut so it is removable for doing blind cuts when the blade doesn't cut all the way through. The splitter give the stock a slight push towards the fence to hold it straight and also opens the cut to keep the wood from burning. i use pine and oak and it has really helped in preventing burning. I use Forrest and Ridge Carbide blades most of the time, but if doing a lot of ripping, I use a Freud rip blade.

CPeter

[Tom Jones III]

With all due respect Dave. I have never come across any one recommending a parallel fence to blade geometry. where have you seen this.

Check my thread titled "Why is my rip cut burning"
http://sawmillcreek.org/showthread.p...hlight=burning

In responses to that thread having the fence parallel is mentioned. BTW, my rip cuts were burning due to operator error - inconsistent feed rates.

[Dave Falkenstein]

With all due respect Dave. I have never come across any one recommending a parallel fence to blade geometry. where have you seen this. The real danger is not being dead on parallel and having the board pinch between the blade and the fence ( if you toe out you never have this potential problem ). I am always open to learning and if you have some info on alternatives I would welcome them. I understand the rational about left of the blade setup, but I have never had a need to do that yet.
regards
Lou

Lou - The owner's manual for the Jet Xacta fence states:

"The fence should be even with the miter slot from front to back".

There is absolutely no mention of setting the back of the fence away from the blade or miter slot in any of the Jet instructions. I have two different Jet fences and both owner's manuals give the same directions - parallel to the miter slot.

I have read numerous forum threads about fence alignment, and I have come to the conclusion that setting the fence parallel or toed out a few thousandths is a choice or a preference. Certainly, the fence should not be toed in toward the blade. If you can measure a few thousandths of toe out, you can measure parallel just as accurately. If a person is not confident in the measurements, then a slight toe out would be preferable.

[Jason Morgan]

Lots of good discussion, sounds like a hot topic (again).

To those of you remarking at the measurements, I am shocked also. Every time I measure it I think " come on...that cant be that close" but it always is. Blade and miter slot are dead parallel for the same tooth. Arbor is good, also within the same 0.002", but I havent checked the blade runout side to side. Never really thought of this as a problem since the blade is spinning so fast that it should even out.

Tom,

thanks for the link to the thread good information there. I noticed (as Jim also suggested) that most of the burning is happening when the piece exits past the rear of the blade. I have a feeling that the fence is aligned properly front and rear, but is slightly bowed. Most of my wiggle in the reading comes in the middle and I think I have a "high" spot that lines up with the back of the blade.


Thanks again all for the insigts, Ill have more details when I play with it some more tonight.