[JFettig]

I have been running belt drive for a while, really nice. Quiet and a little higher RPM.
Too bad I dont have many good pictures of that setup. but I have a few pics of my new setup
The pictures are of my first setup, what you can see of it anyway.
Then pictures of the motor and mount I made, along with the cnc'd double pully I made at work.

I am now waiting for the 2 1/2" vbelts I ordered from mcmaster, they shoudl be here around wednesday. i set it up ontop with one 3/8" belt and turned it on very carefully, it sure is scarry spinning that spindle at 8000rpm
I turned it on slow and tried to stop the spindle like I can normally do with my other motor and it kept spinning!! I have about 3x the power and close to 3x the speed!
I plan on making a 2.5 and 3" pully to try out different speeds. a lot of what I do is in aluminum so I think cutting at close to 30ipm will be fun


How fast have you guys cut aluminum with your machines? I cranked mine up last night(turbocnc override controlles are really goofy), I had it cranking the part out at 10ipm and finishing pass at 18ipm taking .0625 passes without coolant.

You can see the fixture I made for this.
The fixture had a 3/4" hole in the center I carefully made to center with a indicator as my origin, worked great, the 2 bolts at the ends were for clamping the peice down and the holes in the middle area were for that too.

I first put the peice in, clamped it down, drilled my 4 holes, then screwed the peice down into the fixture. Then I milled around it and milled the center part out, and on the bottom peice I drilled and counterbored the holes that I mount it to the mill with.

I drilled and slotted the motor, that was a pain in the butt as the whole motor was like one big magnet, I covered it up real good, taped over everything. I did this by hand with a hand drill and then connected the holes with my RTX.

I have about 1/2" of travel of the motor, I need to do a few calculations and I should be able to use the same mount position for each pully size but it might be a squeeze.

Enjoy
Jon

[JFettig]

I took a few more pics

[jimbo]

Nice setup. How did you adapt the pulley to the mill spindle? Was this difficult? Any details about this portion would be great.

Jim.

[JFettig]

I completely gutted the head and filled all the extra holes with epoxy. overall it was kind of difficult, but it wasnt that bad. If your inexperienced it could be rather difficult like it was the first time I did it.

On the regular setup therses a black spacer under the spanner nut and thats about all that is there that sits on top of the top bearing. For my last setup I cut that spacer down and placed my pully ontop of that and held it down with the spanner. With this one, I removed it all together, I am hoping I wont have to cut a keyway on this pully because I dont know if I have the proper stuff for a metric keyway at work. I will be trying it out to see if it will slip under load.

Jon

[Swede]

Looks great! I've always preferred belts for smaller machines. I think they're quieter, more forgiving, and easier to modify.

I too have an R8 mini-mill spindle that is begging to be put to work. I've torn it down to the point where a bearing change may be possible. The R8 spindle itself could be the basis for a nice spindle using some precision bearings, replacing the adequate but lower-precision Chinese bearings. I've checked the runout of the R8 bore, and it is pretty decent, probably around 0.0003".

In my never-ending quest for small spindles, I recently bought an ER16 cartridge spindle from a guy named JIMSONCHAN in Singapore on eBay. This guy sells quite a bit of hobby-oriented motion hardware. The spindle seemed very nice until I applied a DTI to the bore and found a full 0.001" runout. Unless I regrind, it'll never see use. :tired:

Jon, I just noticed what appears to be FIXED TOOLING in your very first picture!! Tell us about it!

[JFettig]

Oh yes, the Tormach tooling system! It is precision ground and very short, rather low cost too! I have been wanting to find the time to write a review but have not been able to.
www.tormach.com is where I got it from, Greg is very helpful. The tooling system uses a regular 3/4" collet(or the flat ended one you get from him). The tool gets pressed up against the noze of the spindle creating high pressure and high acuracy. I have 2 ER-20 collet holders, 2 EM holders and a drill chuck and am very pleased. Im thinking about buying another 3/8"EM holder for my edge finder because they are so cheap(price) and 1 or 2 more ER-20 holders and a larger drill chuck. I need to sell some of my steppers before I do that.

I must say I am rather satisfied with this tooling system, He said the holders shoudl be fine at 8000rpm and the ER holders should be good way up there(40,000rpm)
Heres a pic of my old mill stand and my R8 collet rack I am currently using. The back 3/4" EM is what I use for facing for now, I made a little adapter that is just like the other holders that has a set screw to hold it on there.


Jon

[Swede]

Wow, I wonder how I missed that system. I'm constantly looking for fixed Z tooling systems that are both small and priced well. This setup looks very nice. Thanks for sharing.

[JFettig]

oh man, this morning I hooked up my motor and it spins so fast it scares the crap out of me!
I am gonna put a belt sheild on there becuase its just scarry!
I have a short movie, it doesnt do justice without sound, the motor is rather quiet but the sound is what makes it so scarry and fast sounding
I have a short video here: http://jfettig.wc101.com/cnc/hss.mov

Enjoy
Jon

[JFettig]

Well, I took my first cuts, 2fl 1/4" carbide .05" deep max speed 35ipm!!!!

It cut a rectangle 2x1" in 16 seconds:The bottom of the path doesnt look to pretty, mad deflection at that speed, I supose with coolant it wouldnt be so bad
Im supprised it cut that nice and at those speeds, my rapids are at 60ipm to keep from loosing steps, it has the torque!

I spun the spindle at about 1000rpm and still can stop the spindle but it is harder. Its also nice how it will start up again when I let go unlike my other motor.

The belts get a little warm, they kinda scare me flying at that speed, I have to tighten them up a little more because they wouldn't fuly extend. How hot can I let these get? they arent hot hot but Im sure a longer cut time will get them rather hot.

I will have to get a video, possibly one with sound another day.

Jon

[Swede]

Hi Jon, I wasn't able to watch the movie (my own PC is at fault) but the photos of your setup look excellent. I think you've discovered that belt tension is critical when spinning at 10,000+ RPM. Hopefully you've got some ability to adjust tension. It would be optimum to be able to adjust it on the fly, because as you dial speeds, the dynamics/harmonics change.

My own Sherline spindle refit suffered a big drawback. I was going to use a Mini-mill motor, and worked hard to create a nice setup. I installed the speed controller behind the spindle backplate, and a bracket to hold the motor. This bracket runs on an RSR12 rail, with a handle to adjust belt tension. Two Sherline belts in tandem deliver the power.

After the entire thing was together, I ended up smoking the motor. I have no idea why it failed, as it was tested a LOT on the bench with this particular speed controller, and it was quiet and powerful.

The photos show my original, screaming-loud, uber-high-speed DC motor, which fortunately adapted to the same bracket. This setup works; haven't cut with it yet, but the noise just bugs me. I may try another mini-mill motor at a future date, but for now I am going to go back to my KaVo 4041, whose only drawback is an inability to handle a number of different shank sizes, since the colet system is proprietary.

[JFettig]

Well I have had the motor running for close to an hour and its EXTREMELY hot the belts show some weird ware, Im turning it way down and cutting slowly so I can finish what I am doing.

Jon

[cncadmin]

Oh yes, the Tormach tooling system! It is precision ground and very short, rather low cost too! I have been wanting to find the time to write a review but have not been able to.
Jon

What did that set-up cost you?

[JFettig]

The whole set with shipping cost about $225 I think.
Well worth it!

I will sandwitch the spindle motor with fans and see how that does running full speed for an hour, then maybe Ill build an encasement for the head assembly or just the motor with a fan or two.

Jon

[napalm03]

I have the same motor, and yes they run VERY hot, I placed a small metal fan from a scrap motor on the small shaft at the top. then made a shroud to go half way down the motor, it only gets warm now even after a few hours.
The motor has very nice torque to be sure.

[napalm03]

Also, Jon, the brushes wear a little funny, if the motor starts skipping out on you in a couple months, dont buy a new KBIC controler,, like I did,,adjust your brushes. Im looking for replacments for mine . If you find a source, let me know, I will need some at some point.

[ViperTX]

JFettig,
How is the finish on what you're machined with the mini-mill....I keep hearing that people are having trouble with the surface finish on what they have milled.

Thanks,
Paul

[JFettig]

I have awesome finish on parts I run finishing passes, and even without finishing passes I have rather good finishes. Take a look at my motor mounting plates, and other parts I have in the photo gallery.

Jon

[jimbo]

Are you still using the original bearings in the spindle? Do you think they will hold up to 8k rpm?

[Falcon]

Hello . new guy here. I have a mini mill, and want to know what is the advantage of hi RPMs? I work with aluminum, and have not had to much trouble milling it. I plan to CNC my mill in the future.

Thanks.

[ViperTX]

The rate at which material is removed (cut) is increased, therefore you can cut at faster speeds (inches per minute - feedrate).