Dremel Mill lives!!

[Taz575]

So I wanted to figure out some way to use my Dremel to cut slots in Micarta and G10 to use as guards on hidden tang knives and also to do the tang slot for kitchen knives on a Wa handle. I found a precision Router base for Dremel tools used in guitar building, but the too many screws kept loosening. I got a cheap $33 linear rail/carriage set on Amazon, but the round bar was coming off of the aluminum base and flexing, so that was no good. The springs I used were way too stiff, but there was a lot of wobble in the dremel platform, so I decided to build a new version!

Version 1:




Bit the bullet and bought the 3/4-12 tap ($22)and the 21/32 ($15) drill bit for it for the Dremel threads and a piece of 3/8" thick aluminum (3x12x3/8", $21) (easier to drill and tap) to mount the dremel to. I used a 7/8" bi metal hole saw bit (Harbor Freight) to drill the holes for the 8" long 1/2" black npt pipe (Ace hardware) so the aluminum could travel up and down on the pipe. Got some 1/2" pipe clamps at Harbor Freight ($6 each) and some 1/2" pipe flanges (Ace hardware) to mount it to the wood base and some springs to go over the black pipe at Ace hardware as well. I got a 30mm linear rail with 4 carriages (only used 2, didn't need the wide version) on Amazon ($40, https://www.amazon.com/gp/product/B093KRZ2N1/ref=ox_sc_act_title_5?smid=A2COIW4JKWLTTA&psc=1) and a very $12 cheap small drill press vise at Amazon as well (https://www.amazon.com/gp/product/B0721SJ54L/ref=ox_sc_act_title_1?smid=AKUDB64FRJA68&psc=1) Some wood screws completed the package.



I will mount it on a better base soon, but it does work pretty well!!

3/32" slot in 3/8" black/red linen Micarta:


I sanded the sides of the micarta to get rid of the fuzzies left over from milling.

Dremel Tungsten carbide bits (9901, 9903 style) didn't do too well. Amazon 1/8" shank rotary burr set did decently and has a wide range of sizes. 1/8" shank, 3/32" 4 flute carbide end mill worked great! I tried drilling a pilot hole and then milling, but it worked better w/o the pilot hole and just lowering the bit until it went slightly into the material and then lower 1/2 turn on the handles at a time. Maybe 2-3 minutes to mill the slot in the 3/8" material. It seemed to work better to pull the vise towards me on the rail instead of pushing away.

I tried some thick metal bar, either 410 stainless or nickel silver and the bit wanted to flex and wander, but it works pretty slick for synthetic materials!

 

[fitzo]

Nice creativity!

 

[52 Ford]

Nice job! Looks like it works really well.

Edit: NOT THAT YOU ASKED... BUT.....................................

I have a couple suggestions if you want to hear them.

I'll assume you do, and go ahead and start yapping.

You mentioned you're going to make a new base plate. T slot aluminum extrusion could work well here. Otherwise, a big aluminum or steel plate with drilled and tapped holes would be easy (if expensive).


Pay attention to this next bit!

You want LESS flutes. At higher RPM a higher flute count is taking smaller chips (more like dust) and doing a lot of rubbing. Insufficient feed pressure just makes the tool rub, get hot, and get dull. Plus in something like titanium or stainless steel it'll make the make workharden pretty bad. You can also buy single flute endmills.

With the 4 fluter at high RPM you're going to need more pressure to get it to make a cut - hence tool deflection.

If your endmill is "walking" when you're trying to plunge cut, you might want to try drilling a starter hole.

A brace at the back of the dremel (back, as in where the cord comes in) wouldn't be a bad idea. Aught to increase rigidity. Not sure you need it, but it sounds like a good idea to me.

I like your height adjust mechanism a whole lot. One improvement I think you could make would be to put a sprocket or toothed pulley in place of the hand wheels so you can couple them with a timing belt or roller chain. That way you can turn one side and know that the milling cutter is going to be perpendicular without have to do much measuring or counting turns.




Sent from my Champion Forge using Tapatalk

 

[Taz575]

Thanks for the insight on the 2 vs 4 flutes! I will get some of those bits, too. I don't like metal guards, so I mostly use Micarta and G10. I drilled a pilot hole thru the material, put the bit into the hole and then put the piece in the vise, with the bit still through it, but I had some wander. When I went straight into the material, I got a much more consistent slot. I didn't want to push too hard into the bit with the metal I had (I think it is 410 or 416 SS, 3/8" thick). Even turning the height down until it hit the material caused the bit to flex, but it's also a 3/32" bit. The dremel itself is pretty solid and tight into the 3/8" aluminum, so I don't think it needs the back brace. The flex was in the bit end itself.

Oooooh, I like the sprocket/timing belt idea instead of the hand wheels! The wheels worked well since I would do each pass a half turn lower, so it helped me take smaller bites in the material, so I may look into this in the future.

I am going to use a better wood board now that I have an idea of how well this works. Aluminum or steel would be pricey and the base would be fairly large, like 10"x13" or so. I have the back end of the rail hanging off the board currently.