Started on a High Speed Spindle cartridge

[jacampb2]

Well, in my spare time for the last week I have been working on a high speed spindle cartridge for my B'port S2 CNC mill. I started with a Chi-Com ER32 straight shaft chuck, 20mm shaft. The bearings are just plain jane 6005RS for now, if things work out I will be upgrading them to ceramic for the high speed durability.

Most of my ideas came from the knowledge in here, and on the home shop machinist board. Many thanks to all who have posted their work. This is not the prettiest creation on the planet, but I am working to the best of my abilities, so no crap about the finish, okay?

Originally I planned to drive it from a little axle I machined that would thread into the existing threads in the end of the ER32 chuck. I made a little spud that threaded in, held the timing gear, and then a 3rd 608RS skate bearing at the top that was going to seat in my #30 QC shank I am making to fit the mill spindle. It turns out that the threaded hole in the shank is crooked, so I had to scrap that plan. First two pics show it with the little stub axle and 3rd bearing.





Today I scrapped that, and bored the cartridge out larger to fit the timing pulley. Then over to the OS Gorton and I milled away part of the center of the cartridge so the timing pulley could go in the middle.





I don't think there is going to be enough clearance in the bore for the belt (I will see when I get a belt) but if not, I am going to have to open up the bore some more-- is it going to be a PITA boring the interrupted bore now? Probably, hopefully I wont have to take much out, if any.

The aluminum piece is meant to act as a heat sink, and help shield the lower bearing from swarf, I may put a felt washer in there to further protect it. The drive is going to be provided from a full size 2HP router, and I will use .75" aluminum for the "outrigger", the upper aluminum piece will clamp around the upper bearing and provide heat sink for that as well.

Anyhow, I think I am making decent progress. The timing pulley did no come out the greatest, and I will probably have to remake it, but I need to get a belt first...

(cont. next post)

[jacampb2]

Well, I made some more progress, but I am still not done. Ran out of time on my days off. Here are some pics:





Started working on the tapered half of the cartridge that will fit the #30 QC spindle. Turned major and minor diameters, did the rest of the machine work the next day.





And I somehow botched it up. I could not test fit the taper until I finished all the machine work due to the flange and "ears" When I got it done, the taper is right, but I think I am a little toward the "small end" of the taper and in the mill spindle the flange keeps the taper from seating all of the way. This wouldn't be a big deal if it were a draw bar spindle, as I could face the taper side of the flange and get it to seat a bit deeper, unfortunately, the QC variant uses a lock nut that needs a fairly precise flange thickness. I don't really want to re-machine the whole damned thing, but I may have to. I am going to try facing the flange first, then if I can get it to seat, I may build the lock nut side back up with weld and re-machine it... Other than that snafu, it is exactly like the piece I have envisioned in my head...

Later,
Jason

[jacampb2]

Well, I made a bit more progress today. I faced a bit off the taper side of the mounting flange, and the taper seats fully now, but, as I was afraid, the lock nut would no longer tighten it, so I welded up the other side of the flange, ground a bit to cut the new groove at it's full width. Almost .375 wide, basically a overgrown parting tool, or form tool to cut it.

I cut the new groove, cleaned up the notches for the spindle ears and bingo, it fully seats and the 1/4 turn lock nut engages it fine.

Next on the agenda, cut the mounting plate for the router which will drive it and find an appropriately sized belt.

Here are today's pics:







Later,
Jason

[creep_pea]

What are you going to use it for?

[jacampb2]

Originally Posted by creep_pea What are you going to use it for?

I do a lot of artsy acrylic engravings. Check out this thread for some of my better work: Machine Created Art: Clicky.

I've been using various rotary tools for a high speed attachment, and it was just time to build something more permanent and that I could have a bit more control over. I get back my full machine envelope, and w/ a ER32 chuck, I can use my existing collets.

[jacampb2]

And now for today's progress:

Well, I'm almost there. I have a bit more work to do on the router mount, I miscalculated the spindle nose location on the router, and it was to low to line up with the pulley in the high speed cartridge. So, I am going to machine a riser block to get the router up a bit. Other than that, I have to make pulleys, and get a belt and I can test it out.

Here is today's progress:





Later,
Jason

[jacampb2]

More today, the router mount is all in, the Z axis drive seems fine with the extra weight. I'm ordering a belt from Mcmaster in a few minutes, should have early trials tomorrow if Mcmaster provides their customary quick shipping to me!

I'm absolutely stoked to have this near done. I have acrylic work that has been waiting for me to finish.

Here's the pics:





Later,
Jason

[TOTALLYRC]

Hi Jason
Be very careful when turning that on for the first time. The basics look good but running a belt from the router at say 20K rpm could shred it instantly. If the router is variable speed start slow and go from there. If you are making the router pulley yourself be extra careful. If it is out of balance just a little bit it could suffer catastrophic failure at high speeds. Flying chunks of aluminum can ruin your holidays.

Your design is very similar to something I have been working on for awhile but have not got around to machining yet. I like the idea of the cutter being under the center line of the existing spindle so if you need to change to a larger cutter you don't have to play with offsets.

Mike

[jacampb2]

Good point! I have a variable speed control I rigged up, I will definitely take that route when I fire it up.

I know of at least one other guy that is running a very similar spindle to this, and he is belt driving it via router as well. I'm not breaking any new ground here, in all actuality, I got the original idea for this design in a thread on this board. Someone posted a magazine article of a HSS belt driven by a dremel. Not enough power for my taste, but it planted the seed!

Ill let you all know if it blows up in my face, I've been there before!

Later,
Jason

[jacampb2]

Well, it is time for another update, I finally got this thing working! I made several failed attempts at turning a shaft for the router pulley, the router is fairly old, and only had a .25" collet. I wanted to step up to .5" bore on the driver pulley, so I turned several shaft for the router. They were all much to far out of balance to use. The last attempt was the best, turned between centers, but I bent it a little bit when I threaded it for the nut to retain the pulley. The first two pictures are of the home made shaft and pulley.

In the end, I ordered a pulley w/ a .25" bore from Mcmaster carr and used a broken EM for the shaft. The $11 for the pulley was much cheaper than the 3 days or so I spent trying to make it myself...

A couple of interesting notes, I had originally planned on using HTD belt drive, as the pulleys are fairly easy to make. It seems that everything else about HTD is a lot more expensive. XL timing belts are much cheaper (about 25% of the cost of HTD) I had a spare XL belt kicking around the shop, and happened to try it on the home made HTD pulleys. It is nearly a perfect fit. The HTD has a round tooth profile, and 5mm pitch (.19685 inch pitch), XL has a trapezoidal tooth and .2 inch pitch. I decided to run the XL series belt on my home made HTD pulley. I turned the OD of the pulley down a hair bit further than it should be for HTD. I would not do this for an actual synchronis drive application, but for just power transfer, I think it will be fine.

Anyhow, the pulley I ended up ordering from Mcmaster was a 14 tooth XL pulley, it drives the spindle fine, even under load.

Here are the new pictures, the first two are the failed router pulley attemps:












Later,
Jason

[Nastyzen]

Nice project!I like the possibilities of torque and speed adjustibilities in your design.It is also good if you have a short Z travel, witch is not my case.I also like the idea of attaching the assembly to the mill through the bat40holder,more accurate and repeatable for touchy jobs.Mine slides onto the quill shaft and bottoms on bottom of the mill body.
How do you keep the assembly from spinning around?
The alu. block cost me more than the porter cable cut out tool.But This was only a first proto to get things working.I'm sure it won't last long carving for hours on end.he he
My original idea is to mount a quality adjustible router with 1/2 collect witch you can buy for 350.00$ and mount the same way.
The proto works great on wood and alu.But is a noisy affair.There has to be a better way than shopvac on top as well..
For now I use hot glue to keep my brush on the adapter.It's from a car wash power washer that I chopped up and it even has a 1/4 turn snap to remove it.
Don't hurt yourself while testing!
Best off luck

[jacampb2]

The spindle brake keeps the cartridge from turning, and also has the benefit of interlocking the main spindle motor. My spindle brake is in good enough condition to stop the main 2hp motor dead if engaged. There is about 3-5°'s of play between the main spindles splines and the dogs, but since the cutter is on the center axis of the original spindle, it should not pose a problem. If somehow cutting has enough force to overcome the brake, I will had a linear rail type device on the router end to keep it from moving.

Later,
Jason