Fun with fences... New face and worse than before

[Jonathan Freinkel]

http://i972.photobucket.com/albums/ae201/Impact-Vecor/IMG_20150531_194806_zpsezs2esxk.jpg (http://s972.photobucket.com/user/Impact-Vecor/media/IMG_20150531_194806_zpsezs2esxk.jpg.html)
I seem to have no luck with this saw.
I was ripping several pieces today and noticed that the width was totally inconsistent.
The next step I took was to lay a level against the fence and it was not pretty. I have gaps as large as 1/8" in the center. The face is new and I know I can shim it however the other side is hard to get parallel.


Should I strip the plastic off and replace with plywood like it previously had?
Any thoughts or advice is welcomed.

[Ethan Melad]

Are you sure the level is straight? I know at least one of my decent longer levels is not, and pittsburgh is a HF brand right? I'd joint a good piece of maple and use that if you don't have any other reliable straight edge.

Do you ever use the right side of the fence for ripping? I know i don't, so I wouldn't worry about that side at all...

[Jamie Buxton]

If you're going to replace the plastic face with wood, I'd use solid lumber instead of plywood. That's what I did. The steel part of my fence is not straight. I put the wood face on, and then straightened it with a hand plane. Can't do that with plywood.

[Brian Henderson]

You need to make sure that your fence itself is dead flat and parallel to the blade, then you need to make sure that whatever you are using for your face is equally dead flat and parallel to the blade. If they aren't, as clearly yours isn't here, you'll never get good results. Whatever plastic you're using, which looks like UHMW, you should run it across a jointer to make sure it's dead flat. I also wouldn't use plywood, I'd go for a good hardwood. You shouldn't have any gaps at all when you're done, it should measure exactly the same to the blade, or perfect when set against the miter slot. It isn't luck, it's just having the proper set up.

[Justin Ludwig]

I replaced my UHMW face with laminated MDF. Made all the difference

[Ed Aumiller]

As Ethan said... be sure the level is straight..
Compare your fence to the miter gauge slot... it will be straight...

I prefer the plastic fence ONCE you have it straight and exactly parallel with the miter slot...

Also, be sure the miter slot is exactly parallel with the blade... this should be your FIRST step then align the fence..

[John McClanahan]

My plastic face was wavy, like it wasn't laying flat between the screws, so I replaced it with plywood. In your case, it looks like the metal tube is not straight. If you remove the plastic, how does the level lay up against the tube?

John

[Peter Quinn]

I'd be checking the level before anything. Harbor freight is not my go to for precision measuring instruments. As suggested above in lue of a better straight edge I'd compare the fence to the miter slot, though the top edge of that could be worn on an older used saw. You could also lay it down on a jointer table if you have one long enough. And don't clamp what ever you use to the fence, this could introduce distortion.

[ian maybury]

I'd be careful of the problem J, as if the fence actually is bowed (and it's not the level) it seems likely to set the saw up for a kickback. If you push the work tight to the fence, and then relax for a moment the spring in the wood means it could easily be eased sideways into the saw teeth. If there is a problem it might be that the 'nip' at the infeed end as well means that the effect is not as severe as it could be, but it risks being similar to running with a fence with the outfeed end toed towards the blade, and by quite a lot...

Not hands on familiar with that type of fence, and it seems a bit unlikely there is a problem - but maybe also check the UHMW with a callipers for uniform thickness along its length.

Hard to run with a fence and/or sub fence that's not flat, as it means that (apart from the immediate problems it might cause) changing the facing (if it requires trimmed or shimmed to be flat) is likely to become a long job rather than routine.

If it is the fence itself that is the problem then i'd really want to change it. (the steel box section) Straightening might be an option at a push. There's fancier but high skill/equipment intensive/riskier possibilities, but if changing it isn't on the agenda then maybe it'd be be possible to do a decent job on the steel fence (both sides) with polyester car body filler? It's do-able with skill presuming the layer of filler didn't end up thicker than a skim - but you would need a long and reliably flat surface, self adhesive abrasive and a good straight edge - and to take it very steadily. It'd need to end up flat and without not just any bow but also with no twist - and definitely not be used unless it ends up truly flat and sound...

[Brian W Smith]

We'd straighten the steel fence here,shouldn't take more than 15-30 minutes to fixture and set up gaging equip.

But that's not to say the approaches posted above shouldn't be done however,it would be an adjunct to a tuned foundation of sorts.

[Don Jarvie]

How far off is the width and where on the board is it? If you rip a 4 ft board 4 inches wide is it 4 inches the whole way of thinner in certain spots. It may be worth figuring out where the problem is on the wood and then shim where it needs it.

[glenn bradley]

All good advice here so I will just add my two-cents but first let me emphasize that using a non-true feed path on a tablesaw is asking for kickback:
- For setup on a tablesaw I align the blade to the left miter slot and then align the fence to that same slot.
- Your level may not be straight; Harbor Freight or not, there are a lot of things that can happen to a level to make it not straight. A jointed piece of hardwood is a good temporary solution fro a straight edge.
- Your UHMW plastic is just conforming to your fence tube. If the tube is really that tweaked I would remove the faces and float some bondo on that thing and flatten it out. Shimming is another ooption but sub-optimal when using UHMW of MDF or anything else that is that flexible in that shape/dimension.
- I avoid hardwoods for reference surfaces because around here, they move. Properly supported MDF (with a good finish of shellac and wax) or UHMW would be my choice.

Bottom line; get a good reference surface on your tube before you mount any face material. Sorry, no magic pill.

[Marion Smith]

That level is probably bowed on purpose. Not all levels are straight. My 48" level is bowed, its a level, not a straight edge. Take the level and stand it up as if you were going to check the level on the saw table. Scoot it against the fence. Is the gap in the middle still there or is it gone now? You may have arbor shaft end play as the forces of the wood grain stress the blade from side to side as you feed the wood thru it. Do you have blade stabilizers sandwiched onto the arbor shaft? The blade may be flexing as well. Last but not least, a dull blade can make any saw cut like crap. Not being critical, just giving ya some troubleshooting tips. Its basically the science of figuring out what its not that leads to what it is!

[Jonathan Freinkel]

Thanks to everyone that replied. I think I tried a good number of the suggestions and finally got it sorted out!

I fence face was jointed and dead straight, no difference. I put the micrometer on the fence itself and it was fine. I replaced the face with plywood and noticed it was the same.

At that point I thought it was the metal fence frame. I decided to sand the face and worked out that where the screw's were had pulled forward. Those inconsistent variations caused the face to ride on the high spots.

A bit of work with a bastard file and we are flat. Put the face back on and all is well!

Thanks again to everyone who contributed!