Enco Compound Slide Table

OOPS! For small angles cos(x) is very close to 1, for small angles sin(x) is very close to x

I bought one of those sets and checked a wide variety of combinations against a B&S 1x1.5 parallel and other pretty good pieces I have using a Fedral dial gage with 0.0001" divisions. Couldn't find _any_ combination out by as much as one tenth. NB: Cleanliness is way ahead of Godliness here. Doesn't take much crud to make up a tenth!!!

Ted

Reply to
Ted Edwards
Loading thread data ...

Which kind? The runout indicators with the lever input which moves in an arc, or the ones with a shaft passing through the back which moves in a single straight line (plunger style)? The former are designed so they provide accurate measurements only at a specific angle of the lever to the workpiece surface. They are mostly good for relative indications (e.g. runout while you are truing something), not for absolute measurements. The plunger style, however, is a bit better, with no cosine error to deal with (if properly mounted).

Even the Chinese rectangular gauge blocks are spec'd to be within 0.000,050" (half a tenth), and I would expect them to meet that spec, so you are unlikely to have a combination which will come up to the resolution of the dial gauge unless the distribution of the sizes is really bad (not a true bell curve).

However -- other sets can be purchased down to 0.000,002" IIRC, at significantly higher cost. No need for these for my suggested use, of course, since the dial indicator is a 0-1.000" one graduated in "0.001" steps.

Amen!

Enjoy, DoN.

Reply to
DoN. Nichols

Plunger. You can see a photo at

I would say a lot better. In use, I mount the DG in my height gage and use a square to set it orthogonal to the surface plate. A half degree error would be very easy to spot. 1-Cos(0.5degree)=0.000038 which would give 38 microinches/inch of travel. I am using comparison measurements which involve much less than 1" of travel so I expect the cosine error to be rather small. :-)

Note that mine are the Chinese cylindrical ones you mentioned. A handy feature of these is that they can be (carefully) joined with Allan screws so multiples are easy to handle when used as you suggested earlier.

Ted

Reply to
Ted Edwards
[ ... ]

Good enough!

Agreed. Often the setup is rather casual, which is why I didn't make strong promises. :-)

O.K. That is one feature which my cylindrical set does not have, as they are solid. How good are the threads? Those on most cheap

1-2-3 blocks tend to be rather useless -- unless they happen to be a metric size which is *almost* but not quite a common inch size. :-)

Enjoy, DoN.

Reply to
DoN. Nichols

Not bad at all. I can make a stack of three or four and not see appreciable error. Maybe I was just lucky or are they all that good?

Ted

Reply to
Ted Edwards

I finished up two test fixtures today. I was very impressed with the Enco table. It actually worked, and held enough tolerance throughout its range to do what I needed. The markings on the dial indicators were a bit sloppy. Some where not very deep and a little hard to read, but after a while I got used to it. I cleaned it up, and adjusted the gibs, and added a couple of vacuum caps on the ends of the handles to cover those sharp threads protruding through the handles! I lost a bit of skin on both of my thumb knuckles before I figured that out.

I drilled 120 holes, a mix of .028, .054, .093, .125, and .250 across a 4" by 7" phenolic plate. I strictly went by my X, Y coordinates generated from PCB with a precision of .001" and used the (a bit hard to read) dial indicators on the Enco table. I set my zero point at one edge of the board, and to my surprise, everything lined up perfect with the PCB vias across the whole board.

Know lets just see how long this table will last!

Thanks to the group for all the advice.

Terry

Reply to
Terry G

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.