View Full Version : DIY high speed spindle
02-05-2009, 11:11 PM
I am running this project by you guys to see what kind of ideas turn up, as well as to get an idea as to how feasible this is...
I have tried many things for a high speed spindle on my b'port SII CNC. The last generation was a bracket and high speed mini air die grinder that was proposed by someone on this board. It served well for milling and drilling PCB's, but anything past light duty engraving and it just didn't have enough power. Add to that, that it has started to destroy itself from the vibrations (it was a cheap HF grinder, was not expecting great things, but it is really out of balance to run at 50K rpms...), and I need a new design.
I am currently fitting an old rotozip spiral saw in it's place. This is not my long term solution either, but just a stop gap for the moment. I rebuilt the rotozip with new abec 7 bearings. I am not going to clamp the rotozip, but machine one side of it's body flat, and drill through 4 of the case bolts and bolt it to a backing plate. The rotozip should have decent runout w/ the new bearings, but spindle float will be a problem. There is no way to preload the bearings that I can see. Add to that, that the plastic case is "plastic" enough to give under cutting conditions, I hold no illusion that it will be a high tolerance tool.
Anyhow, I am working on an idea based on a picture and a thread over on cnczone. Evidently there was a article in Home Shop Machinist a while back about making a high speed spindle cartridge that is powered via a dremel. I am thinking about doing something similar, but driving it with the rotozip in the next generation. Here is a picture from the article.
Anyhow, I need this to fit a QC30 taper. I am thinking of machining the cartridge for QC30, then fitting a small spindle in the cart. As for a spindle, I don't know what material I need? Is mild steel acceptable, or does it need to be SS like a lot of the folks on cnczone do? I am thinking a pair of ceramic 608zz deep groove bearings w/ some ability to preload. Possibly a spacer between the set and a simple nut on top? I know ball bearings are not optimal, but I have them. Would I be better off to try to find one tapered roller for the lower bearing?
The last question/issue is I would like to use the common "rotary saw" collets like the rotozip uses. They have enough sizes to allow for most small tooling, and it will be satisfactory for me. Do any of you know the specs on the collets, angle, spindle nose thread, and bore?
Tell me if I am on the right track, or what I should consider doing differently. Please don't start a huge bearing discussion, because I don't understand all the technical aspects of it. This will only be for occasional use, and I can't see me needing to run the spindle for more than a few hours at a time.
02-06-2009, 01:32 AM
I made this high speed spindle setup for my x3 mill. It uses a Rigid trim router for power. The cartridge spindle is made from stub er11 chuck. There are 3 bearings in the cartridge. Finned for heat dissipation. A 3mm polyflex belt is used. It'll turn near 44,000rpm.
The spindle on the mill is clamped stationary and the high speed spindle fitted into a 3/4" r8 collet..
Here's the setup-
Here's a vid of the first version which had a bronze cartridge showing how smooth it runs.
02-06-2009, 01:44 AM
Excellent pictures! what bearings did you use? Precision tapered bearings, or deep groove balls, or a combintaion? I assume the cartridge is aluminum?
02-06-2009, 03:44 AM
There are some real cheap brushless spindles on ebay now. Made in you know where but for 1HP for something like $450 you cant go wrong. Air and water cooled available.
02-06-2009, 07:09 AM
Yeah, I have looked at the Keling high speed spindles. The low end is about $400 more than I want to spend. Remember, this is just a hobby, I can't justify paying as much as I spent for the whole mill just to buy a HS spindle.
02-06-2009, 10:34 AM
Jason, yes just deep grooves cleared of grease and using light oil. 2 bearings at the nose pressed on and one floating fit in the rear.
Static runout 1" out from the er11 spindle is .0002". The 7 er11 Collets range from .030"- .250".
It'll run about 30mins before it begins to heat up at max rpm. Some sort of cooling system would be needed for extended running times.
The rigid trim router costs 100$ and has a lifetime warranty so if it ever burns out just go and get a new one. Nice powerful 6amp universal motor with soft start and variable speed-
It's a powerful little spindle. I've also used it on the lathe as an internal TPG.
It's all aluminum except for the spindle which was made from a USA Craftsman brand er11 steel chuck.-http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=308-0018&PMPXNO=8708664
So this project ran me around 200$. Not real cheap.
An interesting project but in retrospect I would probably keep a close eye for a commercial unit first. At 200$ it's probably not worth it to me since I don't use it much. Just have to decide how much of a need you have for something like this to buy or even build.
02-06-2009, 08:48 PM
Steve, thanks again for the info. I have the rotozip already, it is a 4 amp 30K rpm unit. I won't be buying a trim router to power it, so that saves some money. Regarding the spindle, do you think it is outside of the realm of possibility to turn one to utilize the rotary saw collets?
One option for me may be to buy a second rzip off ebay and use the spindle out of it in a new housing. Mine has a splined section between the armeture and spindle section wich should come apart. Plus, it is already a 8mm shaft and will fit the easily available fairly high end 608 bearings out there. I have a pile of abec 7 608's and some abec 9 608's that I have been stock piling off ebay to make linear bearings for a plasma table in the future.
I can get a older model rzip off ebay for under $30... Honestly, super high precision in not nessecary for what I am doing. I was perfectly happy with the mini die grinder except for the lack of power and problems it started developing. I may find that the rotozip alone is satisfactory to me, but I would like to get rid of the z float, because that is problamatic...
02-06-2009, 09:16 PM
Well then I think this project is for you. I wasn't sure if you already had a power source. No need for the er11 collet chuck like I used. I wanted a set of er11's for other uses also so when I did that project I bought 2 er11 stub chucks and a set of etm collets. That way I could use them in the grinder,mill and lathe.
You could easily make a spindle much like an endmill holder that would be highly accurate if you only need to use one shaft size. Then the project is dirt cheap. A lot of guys just use the routers and rotozips as the spindle itself. But that doesn't work real well. Not very rigid, plastic housings etc. They make great motors though and you can gear them up for even higher rpm with a belt driven external spindle.
02-06-2009, 09:35 PM
I use a bison QC30 ER32 chuck almost exclusively in my b'ports spindle. I have a very good collection of ER32 collets going for me. Last night I started searching for a reasonably priced ER32 straight shaft collet chuck. It looks like I can get a chicom unit via ebay for under $50 shipped. This would be nearly as good of a solution as the rzip collets, as I have ER32 collets down to .125" right now.
The problems I see with going with this is first that the chicom chuck is going to be of dubious quality for that price. Second, the shank will have to be machined to fit smaller bearings-- turning it down from 20mm to 8mm for my bearings won't leave a lot of meat, but for small/micro tooling, it should be fine. Issue is, can it even be turned reasonably well or at all. The ad claims hardened and ground shaft, I could buy some 20mm bore bearings, but high precision ones come at a much higher cost, and I am having trouble sourcing any other than ceramic that are rated for greater than 11k RPMs.
All in all, I think the best option is to try to use the inexpensive spiral saw collets and nuts. If that means not machining the spindle myself, I don't think it is a big deal as the spiral saws are cheap and I can rob one for parts.
02-07-2009, 12:29 AM
have been mentioned in the past so I'll toss out the link FYI.
02-14-2009, 07:41 PM
Well, here is my "temporary" solution. It already far out preforms the little air die grinder. It will probably stay like this until it starts giving me issues, or burns up the rzip. Not as pretty as a lot of you gent's work, but here it is none the less.
02-15-2009, 08:35 PM
Might not be the prettiest setup, but judging by the nightlight you posted, it works great!
02-22-2009, 08:06 PM
Here is my solution to a high speed spindle. I took a Dewalt 3 HP router and made a plate to adapt it to the spindle. I needed to add a 1/2 ground rod to hole it steady during cutting. I thought the brake would hold it but there was too much slop in the gear train to make that happen. I also added a limit switch so if the rod is in place the spindle cannot start up. That would be bad if the spindle would try to rotate the entire bracket.
02-22-2009, 10:43 PM
That is well executed. Is that a standard size router, or something between trim router size and full size? It seems a full size router would be to big, at least the full size router I have would be. Why did you decide to make the bracket mount to the spindle instead of the quill? I toyed with the spindle idea, but found that my spindle had about 2-3° of rotational freedom even with the brake engaged. Clamped to the quill, it is rock solid, and you can easily switch to the main machine spindle w/o removing everything.
I am pretty happy with the rotozip. I may still make the move to a quality trim router. It seems the bearings are better, and they don't have as much run out or z float due to the case design and actually having some bearing preload.
The primary reason behind my wanting to do a spindle cartridge was so that I could improve runout and get some preload on the bearings. Secondary, and nearly as big a reason for me was I did not want to give up any working envelope of the machine. On thinking about it more, I can't see myself really needing to engrave, or high speed machine anything that is absolutely going to need that lost 5-6 inches of x travel.
I have a new question, on this topic, but a bit off as well. I hooked up my rzip to a triac dimmer type speed control. I have not used it yet at anything but full speed, but I started thinking about maybe building a PWM DC supply for it instead. Being a universal motor, it will happily run on DC or AC, I am wondering if there might be an advantage to this. I seem to recall that a PWM supply will allow it to have higher torque at lower speeds than the alternative of just lowering the voltage, any thoughts?
02-22-2009, 10:55 PM
The first thought was to clamp it to the quill but my CNC machine has a Fanuc contoller and it need to go home so it knows the range in x,y,&z. 99% of the quill retracts up in the head so if I mounted it to the quill I would need to home and then install it and not leave it on. Since I have about 36 inches of X travel the loss of travel really isn't that important.
It is a full size router but I have three of them and figured I would use it since it was on hand.
02-22-2009, 11:41 PM
Yup, my quill is the same way in it's home position. I am running Mach3 though, and typically I just zero it on the work and go. So far I have not run into anything in Mach3 that forces it to home unless I manually tell it to home. Even then, I have enough adjustment in my z axis limits that I could set the home/limit low enough to work... It sound like you have a good solution to the issue though. I don't see the bar you mention-- How does it lock the spindle and still allow for Z travel? I am just curious, but it may help others.
02-22-2009, 11:52 PM
Here is the side view to stop rotation - and the limit switch. With this setup I have a full 6" of quill travel. In the aluminum blocks are Tompson roller bearings. As long as the rod hits the limit switch the motor contactors are disconnected.
Here is a video showing how the high speed spindle on my CNC mill works.
Here are some pictures of the spindle attachment.