Spindle Cooler -and just chatting a bit...

So... Been doing a LOT of CNC work these days with the PM45-CNC. That machine is getting used far more than I ever imagined. Anyhow, typical RPMs are 1800 to 2800 for most everything I do which, by high-end standards is fairly slow. A typical job can easily take from 45 to 90 minutes and during that time, the external spindle collar gets up to 115 degrees. -Not abnormal at all. The gearbox gets warm to the touch and registers about 100 F. Interestingly enough, the motor stays virtually cold the whole time. It has a forced-air electric fan that blows like a tornado.

Have a look at it...




Anyhow... I decided to make an aluminum cooler ring for the spindle. I also have another trick up my sleeve to force air to move past it but, won't implement that until I experiment with just the cooling ring first.

Here's a few pictures of the ring which is a drops piece of 6061. The holes were drilled in the CNC mill. The center-drilling and bore-drilling took about 8 minutes -which was a long time because I didn't bother to tweak the CAM tool paths to optimize it.

As you can see, it was a solid cylinder to start-out and instead of making bird-nest swarf on the lathe, I milled-out the center -and that gives me a nice little piece of drops to play with some day. I did touch-up the inside bore and face the edges on the lathe though...

I'll let you know how it works. I'm guessing it will keep the spindle about 8-10F degrees cooler.

And BTW, if you have a normal speed mill of this type, don't bother with this cooler contraption. I run my old PM45 for hours at a time at high speed and at 1900 RPM, it barely gets warm to the touch...




And as far as chatting goes...

I might not be allowed to hang around here anymore... With any luck, at the end of this summer, I'm moving into a 1200 sqft industrial building, 10 minutes from the house. I also plan to fill that space with an additional piece of machinery. I'm looking at another very nice CNC mill to help crank-out parts. I'm doing low/medium production runs of some specialized parts these days. I think that might push me out of the ranks of hobby machinist and therefore, we'll have to see if Tony, Bill, George, Marcel, Nelson et.al. will still let me hang-out here... LOL...

Ray

Good morning Ray. I'd like to see a picture of the cooling ring installed on the spindle.

I don't think the fact that you've gone "pro" is gonna affect your status here.) I'm right behind you buddy! With any luck, I'll be doing this full time too.:thumbzup:

xalky said:

Good morning Ray. I'd like to see a picture of the cooling ring installed on the spindle.

I don't think the fact that you've gone "pro" is gonna affect your status here.) I'm right behind you buddy! With any luck, I'll be doing this full time too.:thumbzup:

Click to expand...

Will do. This isn't a priority project but I'll get to it soon enough. BTW, this cooler does not spin; it's located on the external/fixed part of the spindle housing. It's a very slight friction fit now but, I'll probably split one side in the bandsaw and tack a couple screw tabs on there.


Ray

In the picture where you're milling out the center section. It appears that you're using a 4 fluted end-mill to create a slot which (eventually) frees the center section. If that's the case, if you don't mind, I have a few questions...

1) I believe I've read (somewhere) that when milling a slot a 2 or 3 flute end-mill should be used (and 4 flute should be avoided). I think the reason had to do with the cutting edges on the opposite sides being in contact with edges of the slot at the same time. So, I'm curious whether there's some reason that doesn't apply in this situation, or maybe I'm just wrong, or maybe it's just not that big of a deal, or what?

2) When milling out that section, I'm curious how deep each pass was? Also, can I assume that was a center cutting end-mill? If not, was there some other trick going on here that I'm not seeing?

3) How do you deal with the final pass when the center section breaks free? It seems to me that once the center piece is free that it would just cock and jam the mill.

These are just questions born out of curiosity, thanks for sharing!
Good luck with the new shop!

kizmit99 said:

In the picture where you're milling out the center section. It appears that you're using a 4 fluted end-mill to create a slot which (eventually) frees the center section. If that's the case, if you don't mind, I have a few questions...

1) I believe I've read (somewhere) that when milling a slot a 2 or 3 flute end-mill should be used (and 4 flute should be avoided). I think the reason had to do with the cutting edges on the opposite sides being in contact with edges of the slot at the same time. So, I'm curious whether there's some reason that doesn't apply in this situation, or maybe I'm just wrong, or maybe it's just not that big of a deal, or what?

2) When milling out that section, I'm curious how deep each pass was? Also, can I assume that was a center cutting end-mill? If not, was there some other trick going on here that I'm not seeing?

3) How do you deal with the final pass when the center section breaks free? It seems to me that once the center piece is free that it would just cock and jam the mill.

These are just questions born out of curiosity, thanks for sharing!
Good luck with the new shop!

Click to expand...

Hi...

I should have used a 2 flute but, that's what happened to be in the mill so I just used it. It's also just a plain-Jane endmill. For full width cuts like that, it's perfectly fine for the cutter to contact at both sides -matter of fact it's preferred. Each circular cut was 0.25" deep with a 3 ipm straight plunge. Cutting speed was 20 ipm. There was 25PSI of compressed air keeping the chips out of the slot. To prevent the piece from getting wedged on the last pass, I set the program to cut all but the last 5 thou of depth. Then I put it in the lathe and poked it through at low speed.... FWIW, I had a block of wood supporting it from the bottom. My vises aren't big enough to hold a piece that size with V-blocks. I didn't feel like messing around with top clamps. This is/was a very quick, non-critical part...

BTW: Sorry, didn't mean to mislead anyone with my occasionally sloppy techniques but, when working with aluminum, you've got a lot of latitude.


As an aside, I sized the ID of the hole to be 15 thou oversize so I could clean it up on the lathe. Surprisingly enough it was indeed 15 thou pretty much on the money and it was fairly round too.


Ray

... And here's the spindle cooler installed on the machine. -Just cut the ring, welded a couple tabs and used a thru-bolt to pinch it closed.

I'll let you know how it performs once I find-out...



Ray

nice job Ray
my spindle got hot at first but calmed down when the machine broke in, Now it's just warm to the touch after long runs.
have you changed the oil yet?
I ran my mill to warm it up and then drained it, The factory oil looked like something I just drained out of a diesel truck. I think China recycles their oil by sending it to the us in machines.
steve

jumps4 said:

nice job Ray
my spindle got hot at first but calmed down when the machine broke in, Now it's just warm to the touch after long runs.
have you changed the oil yet?
I ran my mill to warm it up and then drained it, The factory oil looked like something I just drained out of a diesel truck. I think China recycles their oil by sending it to the us in machines.
steve

Click to expand...

Hi Steve...

Yes, I just changed the oil. It wasn't all that bad but had the usual amount of residue, paint chips and some grit. I did in-fact run it at high speed for about 5 minutes to get all the grit suspended. That's a good practice. And of course, I got a fair amount of oil dripping down my elbow getting the plug in and out. And of course, during the procedure, I dropped the plug and it somehow rolled half way across the shop from where it fell. -Sheesh...


Ray

Very cool! and Awesome news about moving up in the world of CNC, I really, really need an excuse to buy a 45 CNC...

Was that what you had to go and tig weld yesterday?

Im sure the good folks will keep you around once your making chips with the big boys...It's more of a matter of whether your even going to have time to even cruise the forum!

Jamespvill said:

Very cool! and Awesome news about moving up in the world of CNC, I really, really need an excuse to buy a 45 CNC...

Was that what you had to go and tig weld yesterday?

Im sure the good folks will keep you around once your making chips with the big boys...It's more of a matter of whether your even going to have time to even cruise the forum!

Click to expand...

Hi James...

I TIGged a couple things yesterday. A walk-in guy needed a couple inches of weld on a titanium tube. That was easy. I also welded the little tabs on the back of that cooler ring. -Another easy job. I spent the rest of the day, cleaning the shop and working with customers on the phone. All fun stuff.

CNC is fun and a lot moreso than what I expected. I need to work and push myself a little harder in terms of learning more tricks of the trade. The learning curve was steep but, before I touched a CNC machine, I read and studied as much as I could. That really helped.

Ray