Milling a flat straight edge on an aluminum sliding table saw table

[Wes Grass]

The problem with that, Wes, is he is limited to the travel of the table across a 12-18" blade. .001-.002" across a 12" blade plate means his actual error could be 5-10x worse over an 8-10' stroke ..... dont think you need it to be exactly dead nuts perfect over 8-10'.

True. And the blade can only touch the wood over whatever length is engaged. So a couple thou', regardless of what the travel is. You set your crosscut fence to that, and parallel guides if you have them.

As a perfect example of the effect, consider a sliding table on a router table. Makes no difference what direction it's pointing if it only engages line contact, vertical, with a round cutter.

On the table saw, you'd get a cove shape to the cut if you ran it at an angle. But it would be straight along the length of travel. Of course, a thru cut would be a problem with the blade getting bound up in there. And that's what you're trying to avoid by aligning the table to the blade.

A dead straight edge on the table will read zero on the indicator no matter what the angle of travel is. You want it referenced to the blade.

An extreme example. Your indicator will tell you that's 'straight'.table_align.JPG

What you need to do is this:t_align_2.JPG

The indicator goes on the sliding table.

More.

Sorry ;-)

This is the opposite of a conventional saw. Conventional, you have to align the blade to the miter gauge slot. Unless you have the ability to put your finger in it and pull it over like Popeye moving a knothole so he could see the construction project ;-)

The sliding saw, in effect, has a moveable 'miter gauge slot'. Both the table and the fence get set off the blade.

[Bobby Robbinett]

Ok I will take these opinions into consideration. I never thought about taking a reading from the opposite side of the sliding table.

I do have a Freud setup and calibration disc that fits my slider (had to be modified by a machine shop) and I suppose that I could theoretically clamp a straight edge to it and place my dial indicator on the sliding table.

.i will give some of these suggestions a try and see how well I can get things lined up. I don’t have a track saw or router guide. I suppose that I could get a straight edge and use the router to flatten the inside edge of the aluminum sliding table. Only thing is that I don’t have a good way to use a point of reference to set my straight edge router guide relative to the travel of the table. I still think my idea of using a trim router with a plywood sub base and a guide or fence mounted on the sub base to follow the opposite side of the table will work best.

[Steve Jenkins]

I’m probably not thinking right but me slider has a slot the full length of the table. There is an adjustment point at each end of the main base to allow for adjustment toward and away from the cast iron top. I put the magnetic indicator base on the cast iron top with the indicator riding on the edge of the slot. Probably clear as mud.

[Wes Grass]

One last try ...

If your goal is to align a straightedge with the axis of travel of the sliding table, then mounting the indicator to the fixed (cast iron) table and running the sliding table back and forth is the correct method. It still tells you nothing about where the blade sits.

Steve: Whether the slot in the table has been machined in alignment to the surfaces for the guide bearings is another question. I never checked my KF-700. My guess is 'probably, maybe'. What I *DO* know is that the underside of the T-slot was not machined to make the shoulders parallel to the top of the table. Not normally a necessary requirement for simple T-nuts used for clamping. I made some custom pieces, and had to shim them to get them level. The main feature being a precision bore with a close fit to an insert I put into the crosscut fence so it repeats 'square'. It actually bound up a little without the shims, as the insert was tilted toward the table, I think, a fair bit.

[Mel Fulks]

Denatured alcohol on Al- U- Minium get rid of gummyness and makes for easier cutting, scraping ,and drilling.

[Bill Dufour]

Slop JB weld on the edge to fill any gashes. Then rip top to width on a tablesaw with an old carbide blade.
Bill D

[Michael Schuch]

Does it look anything like this:
20220306_011418.jpg

20220306_011439.jpg

My Casidia saw has some relation to Griggio. I am thinking of adding the shown T track to my saw (it does not have any T track) which would move the aluminum plate over 5/8". To mill a new straight surface on the plate I am planning on clamping the plate to the underlying support brackets and cut a straight edge on the plate half way using a saw blade on the sliding table saw. Then move the plate forwards on the supports, re-clamping then cutting a straight edge on the trailing half of the aluminum plate. From what I have read a wood saw blade should be able to cut an edge on an aluminum plate with no problem. I think this will result in a MUCH straighter edge than a router.

I had also considered using a track saw to cut a new straight edge.

I have used carbide router bits on aluminum previously and they cut the aluminum very well leaving a good finish.

[Michael Schuch]

So who ever the prior owner of my Griggio sc3200b slider was, they apparently ran the blade or something into the right edge of the sliding table a few times. It made that edge rough on almost half the length of the sliding table.

This is making it difficult for me to set up the sliding table parallel with the saw blade as I can’t very easily get my dial indicator to read perfectly throughout the travel of the table because the edge is so rough. It bounces the tip of the dial indicator and messes up my reading. Tried going really slow and it is worse that going fast.

My solution is to mill a straight edge on the aluminum sliding table on the blade side. I am thinking about using my Bosch Colt trim router with a .25” shank 1/4” straight bit and making a wide base with a fence or guide of sorts to register off the opposite side and slide all the way down the length of the table. It’s aluminum so this should work.

Any thoughts from you guys would be much appreciated.

Just curious if you made any progress?

[Bobby Robbinett]

Just curious if you made any progress?

I got it as close as I could. What I ended up using was a set up and calibration disc in place of the blade. I then clamped my 96” Empire level to the back side of the setup and calibration disc and put my T-Track dial indicator in the slot of the sliding table. Then without moving the sliding table itself I slid the t track dial indicator from one end to the other registering on the edge of the 96” level. It’s not nearly as accurate as I would like. But it’s decent.

If I try putting a dial indicator on the sliding table and measuring travel by again referencing off the level that is clamped tight to the back of my setup and calibration disc (thus measuring the travel of the sliding table relative to the blade) then I get readings all over the place as if the table is not tracing straight.

It is what it is. I would love to have a new Felder but right now I can not shell out $10k for a new one. I have, however, considered ordering a Chinese slider that is pretty much a clone of the Grizzly and Cantec style of sliders. I can get one for under $3k and shipping is $875. So that is my plan. Would love to find a deal on a used Felder, SCM, MiniMax, Altendorph, Martin, Cantec, ect.

[Kevin Jenness]

You get what you pay for (usually). There's a Martin T71 listed in the classifieds here for $6k - it's in CT so not exactly convenient but saws like that do come up and in my opinion are a better bet than a no-name Chinese machine. Good luck.

You can measure all you want with a dial indicator, and you may need to use one to make adjustments. Before you do any thing though, does the saw cut a straight line? Cut two 8' rips and put the sawn edges together. If there are gaps between them relating to the indicator variations the table is thrashed and you may as well replace the saw. If not, relegate the level to building stud walls and get a reliable straightedge. If your saw cuts straight enough you won't need to buy one.

[Wes Grass]

If you get a good reading off the level by running the dial indicator down the t-slot, but it jumps and wanders moving the table, it's likely the table bearings are shot. In that case, I'd expect random readings off the t-slot with the indicator on the machine table as well.

What kind of bearings does it have on the table? Integrated linear guides like a Felder, or ordinary ball bearings running on machined rails? If the latter, there may be crud ironed onto the rails making it jump around.

A couple places I worked had Roll-in band saws that would do this on a regular basis. I pretty much had to scrape the rails with a scale every time I was going to use it.