small drill adaptor

So I have on order a Drill adaptor, but is still weeks away. So in the meantime, set about and made one that can use the Dremel collets, or the MultiPro drill chuck. The thread looks to be 7mm X 40 TPI. Mine used a scrap ejector sleeve 12od and 8mm id. A piece of 8mm silver steel was used for the shaft, and the 7X40 TPI thread. Drilled the end with a 9/64 drill and drilled 25mm deep . The front inner taper is from the centre drill, as that is 60 deg included. I put the centre drill to finished depth after the 9/64 drill. A carbide 2mm drill, put the hole through the pin for the anti rotation pin. Used a 2mm roll pin and cut a slot down the 8mm shaft . No return spring has been installed. This one has about 32mm of travel. The Al cover is a slight interference fit, so it can be easily removed with a small amount of heat.

Used a slide hammer to take apart the drill chuck to repair damage to the jaws which it has had from new. Cleaned them up and pressed back together on an Arbour press

Ready to Press back together again.

Neil

Nice one Neil, looks neat, how does it come out for accuracy?

George.

With the collets, I can not see any wobble at all. But with the chuck, you can see that it is not as good as a collet, but the chuck was a lot better after cleaning up the burs and damage , compared to before the chuck repair. I used it to drill 0.6mm oil hole in the conrods of 2.5 cc competition engines. I needed to get some parts made this weekend and latter this week and it has worked well today. The next rods I drill, ill try and do a video to show the concentricity and how it works. Neil

... The next rods I drill, ill try and do a video to show the concentricity and how it works. Neil...



​Geo.

A pin chuck (I think that’s what is called) is good for small diameters, closes to zero. They are on a small diameter. shaft

That is correct. Effective I have made it a pin chuck when it uses the full range of collets from Dremel and the other rotary tool people that have copied , making collets that cover from the very small to the 1/8 diameter. One of the things i did discover, was that the new collet nuts were not as well made as the older one that I am now using. The font taper is not that concentric to the threads on the 2 new ones that I brought. The same goes for the repaired drill chuck. The 1st few times I used it, it ran to look at true. Then when I tried it with a different sized (1mm drill) it was wobbly. I rotated the jaws inside body, so as it closed the jaws moved with the outer body, and found a position where it ran true to look at. What a pain. So it seems there is a concentricity issue in the parts of the mini drill chuck itself. My next mission, will be to make a copy of the parts , and just use the jaws and springs, to make a mini drill chuck that runs true over the range. I don't need any bigger than 1/8 inch from it anyway. I will have the keyed chuck arriving in a few weeks time anyway. But do like the convenience of the keyless chuck. My main use is for small holes under 1mm and allows to feel what is happening. The quill on the ZX45 mill just does not have the feel needed for small drills for me anyway.

I deliberately did not make it with a return spring, as I wanted to have the longest travel possible with the height and still using the 13mm capacity drill chuck. I could make a longer one, with a spring return, but then that would mean using a MT4 collet, or using the ER32 or ER40 collet chuck to hold the adaptor.

Neil

I have made several collet chucks based on the commercial Dremel closing nut, which is cheap to buy, and a home cut taper for the collets, with closing thread for the cap. Works a treat. The collet chucks are integral with shafts on accessories for a grinder, to allow me to hold tiny shafts, drills, etc.

One often quoted size for the Dremel nose thread is 9/32 x 40TPI which is an ME thread size. I have seen that thread spec quoted by a Dremel staff member.

Marcus