Sherline Carriage Dial Indicator Holder

This is a model I made for holding a 3/8" dial indicator on a Sherline lathe to precisely measure distances traveled. This isn't intended to be a fully 3D printed model, I did a lot of clean up work and to get better precision holes that could be provided but more experienced 3D printing people than me are welcome to give it a try. I provided two different size models for my Mitutoyo 0-1" indicator and my 0-2" Shars indicator. The smaller clamp still isn't the ideal size for the 0-1" stem due to the small distance it has to accommodate, so you will lose ~0.125"-0.150" of distance on the dial indicator.

Print Instructions and Settings

I printed this part with 20-25% infill and 3 wall loops. The extra walls were to give it extra strength and allow for more will room to make the holes more precise with drills and reamers as needed.

Since the most critical part of this is the straightness and parallelism of the guide bar and clamping screw holes, I printed the base and clamps vertically to give the printer the best chance of getting the holes correctly. I used tree supports to support the 3/8" hole.

 Print in this orientation.

Hardware

• 3x 3/16" precision ground round rod, 1.5" long

• 3x ~0.180" OD springs, ~0.310"-0.375" long, optional

• 2x 10-32  socket head cap screws, 1.25" long

• 2x #10 washers

• 2x 10-32 thumb screws, cut down to ~1/4" long

• 2x 10-32 heat set flanged inserts, .250" long

Guide Bar Notes

I used precision ground 3/16" tool steel rod since it's pretty and not that expensive at this size, this isn't really critical, feel free to use whatever kind of metal is handiest to you as long as it's around 3/16". The guide bars are there mostly to keep the clamp from twisting too much as you tighten the screw.

Spring Notes

These are optional but they may be just the thing to and some quality of life to the tool. I used 2 0.310" long springs with 0.014" wire diameter that I interleaved together and it kinda sorta works but I really should have gotten longer and stronger springs. In theory, there should be an overlap of about 0.060" but that does not seem to be enough. I don't know what the sweet spot is, but if you use springs, I'd try something a little longer and/or larger wire diameter.

Thumb Screw Notes

For the thumb screws, I took a 10-32 thumb screw from the hardware store and cut it down and turned it down to ~1/4".

Threaded Insert Notes

The heat set inserts are a little unnecessary. For an earlier prototype I just took some 1/4" rod and cut it off to around the depth of the screw hole and then drilled and tapped it for 10-32 and parted it off. I then super glued in the insert. This probably more than enough for the clamping forces you will put on this part and it avoids the problem with the inserts blowing out the sides of the holes and clamp. There is also no reason to use strictly flanged inserts, feel free to edit and update the model to whatever insert style you'd like.

Post Processing and Assembly

As mentioned above, this project wasn't really designed to work straight off the printer. Follow these steps for best results:

1. Heat and press threaded inserts into insert holes, try hard to make this as straight as possible. If the insert aren't seating well, consider opening up the entrance of the holes just a little bit to seat them better.

2. Drill or ream guide bar holes and clamping screw holes

   1. If 10-32 bolt doesn't loosely pass into the clamp hole, open it up slightly with a drill .005"-.010" above 0.190" until it does.

   2. Ream the guide bar holes on the clamp side for a gentle press or push fit on the guide bar, either with a nominal 3/16" reamer or +.001". If guide bars slide too freely on this side of the holder, add some super glue to bond them.

   3. Off the printer, the guide bar holes on the base side should be oversized enough that the bars should slide freely in them. If they don't, open the holes up with a drill just a bit until they do.

   4. Deburr all drilled and reamed holes.

3. Test your dial indicator and open up the 3/8" hole to fit the stem as needed with drills.

4. If needed, chase the modeled threads of the thumb screw with a 10-32 tap

5. Press the guide bars into the clamping side of the holder and bond them with super glue if necessary.

6. Optional: Put springs into guide bar holes.

7. Test fit all your parts and open things up as needed