Lathe toolpost holder for Dremel flex shaft

[mklotz]

He doesn't need to swing the full 3.4" while cutting the thread. Make the part in two pieces.

If I were doing this, I would take a length of about 2" of 1.25" cylindrical stock and thread it 3/4-12. [As long as you're going to cut threads, thread a longer piece with this useful thread size and you can, in the future, cut off lengths for other Dremel-holding devices that you might want to make.]

After threading cut off a slice and cross drill and tap it for some thread for which you have dies. Take a piece of square stock that fits the tool post and turn a tenon on the end and use your die to thread it. Use Loctite 609 to secure the Dremel-holder or silver solder it in place. This threaded joint isn't going to receive much stress in use (grinding is a delicate operation) so a two-piece assembly should work just fine.

[Paul Jones]

Marv,
Really great advice on the construction. I use a lot of Loctite to joined small parts and never a problem. Silver soldering is fun but so much easier and faster these days assembling using a Loctite product.
Regards,
Paul

[Jon]

If you missed the link to PJ's excellent site:

-->Click here for PJ's Mini-Lathe Site<--

[Hemi]

Morsa,

I like your ideas for the Dremel tool mounting on the Unimat. I also appreciate the link to PJs website/blog.

In regards to Hemi's dilemma about not having a welder, that can be easily solved. The nut and shaft can be joined with silver soldering the steel parts (I like this old technique because it is more an art than technology) or making solid piece from aluminum (or steel) and drilling/tapping the thread using a common drill press. Spindle nose on Dremel is either 3/4 x12 or 3/4 x 16 with the 3/4x 12 being the most common. Buying the HSS tap is the most expensive part of the whole assembling but the tap will last you a lifetime for other Dremel adaptation projects.

Regards,

Paul Jones

Paul,
I'm not sure silver solder would be enough to hold it... I TOO thought about that way of doing it but I thing a weld to the nut onto the unused tool bit be a stronger bond..... I have a couple friends local that I'm going to take both nuts (one for the flex shaft, and one for the whole rotary tool) to them with 2 unused tool bits to have them welded.....

Doing a threaded attachment, might be difficult too just because the vibration would eventually loosen the threaded rode into the flat side of the nut, so..... -Maybe I'm not thinking of how it was mentioned here.... -Enlighten me if you would, (I think Marv, made that suggestion there of)

[Paul Jones]

Hemi,

Marv's suggestion is the best approach for construction using two parts. Assuming the Dremel tool post holder is for a 14" or smaller engine lathe, the technique for silver soldering steel parts or using Loctite is very strong when done correctly. The parts can be joined together using a high quality silver solder (remember to use plenty of the special white flux for silver soldering and the heating the parts to almost red hot - you will know when by capillary action the silver solder is sucked into the joint) or glue with Loctite (I like the 620 and 680 products) for a simpler and easier sliding fit construction and let the Loctite do its work. The extra strength of the joint comes by using a side hole drilled perpendicular to the middle (either drilled straight through or perhaps drilled and then tapped with a 1/4-20 or 3/8-16 thread for the perpendicular part) into the side of the part previously made with an ID threaded for 3/4 x 12. This should work as well as just welding on the part on side-to-side.

Trust me, the two parts will not come apart unless you totally crash the Dremel tool into the lathe chuck and most likely the Dremel tool will be destroyed long before the two parts ever come apart.

Regards,

Paul

[mklotz]

Two other remarks to add to this...

When grinding with something as small and underpowered as a Dremel, the maximum depth of cut will seldom exceed a thousandth or two. With such a light cut the reactive forces on the holder are very small.

I know very little about welding but I've never heard of welding to a (presumed HSS) tool bit. Does HSS weld well? Wouldn't a piece of ordinary steel serve just as well? Why waste a tool bit unnecessarily?

If welding will make you feel better, then do it. However, I have to agree with Paul; it isn't required for this device.

[Paul Jones]

Hemi,

I think Marv and I have both shown several examples of using a Dremel or Foredom tools held in the lathe QCTP for precision grinding of parts (e.g., http://www.homemadetools.net/forum/u...6880#post67090 ). In these cases we are only removing 0.0005 inch to 0.001 inch in diameter per pass (actually two to three passes before moving in for another grinding cut) and there is very little side force to contend with.

Regards,

Paul Jones