Another PM940-CNC-VS Thread...

[phazertwo]

Well... I've been busying doing everything BUT working on the mill. We had a knarly wind storm two weeks ago and it put the finishing touches on my crappy fence. 2 days 9 posts, 30 stringers, 240 pickets, 1600lbs of concrete, one earth auger, and two DAMN good friends later, I have a fence again.

It's much improved, not only because it's not falling over anymore, but it also has a gate. That means I can put MORE **** in the backyard!


I also had to do a fire drill re-gear of the front and rear differential of one of those buddies Land Cruiser...

While all that was going on some parts did come in. The new VXB bearings (I just noticed that for some reason the pictures of the NSK super precision bearings are gone..) and they are going to work perfect for a "test" run. The quality is surprising, however they are no match for the NSK bearings.
Left is the upper NSK, right is the upper VXB:

Also, the pulleys for the "test" belt drive showed up:

They are sitting on some 0.5" aluminum plate that I will use to build a "test" motor mount, and the rod to the side is to make a new quill lock. My plan is to get the mill up and running again with minimal machining, since I will have to borrow a friends manual machine to make parts while it's out of action. Once it's back in action, I will re make a lot of these parts, and add a power draw bar, and a two speed system. I will also make special press tooling to allow me to push the NSK bearings in with out messing them up.

Unfortunately progress will likely be slow for a while. We're coming up on our annual trip to Moab UT, and I have to get the truck ready to go. Hopefully I can get some time here and there to work on it, but most likely nothing significant until June...

PZ

 

[TomS]

Do you ever slow down? I'm getting tired just reading through your post! LOL.

I had the same issue with the upper bearing on my PM-932. After thinking a while the light went on and I realized that the spindle drive pulley acts like a slinger and prevents most anything from getting past the splines during operation. This proved to be true because about six months after I did my conversion I opened up the gear head and the interior was as clean as when I assembled it.

I don't remember reading what your upper RPM goal is but seals have a RPM limitation. My upper limit is 8800 rpm. I didn't find any seals that would live at that speed.

Hope this is useful information.

 

[phazertwo]

I try to keep busy...

It is very useful information! I did consider that the pulley would be protection, but my spindle pulley is so small (67mm) that I figured it would still be a problem. What size is your spindle pulley?

Here is the seal I plan to use, should be good over 10k rpm:
https://www.mcmaster.com/#5154t122/=1cp1m10

My goal is 7500rpm on the top end, and I should be able to hit that at 120hz. Theoretical top speed should be 9000rpm at 150hz, but there is no torque up there.

PZ

 

[TomS]

I try to keep busy...

It is very useful information! I did consider that the pulley would be protection, but my spindle pulley is so small (67mm) that I figured it would still be a problem. What size is your spindle pulley?

Here is the seal I plan to use, should be good over 10k rpm:
https://www.mcmaster.com/#5154t122/=1cp1m10

My goal is 7500rpm on the top end, and I should be able to hit that at 120hz. Theoretical top speed should be 9000rpm at 150hz, but there is no torque up there.

PZ

My setup uses a two step pulley. The large pulley is 5"diameter.

16,300 rpm, Wow! When I was looking for a seal the highest rpm rating I could find was about 5,000 rpm. Thought about using a labyrinth style seal but the price was a bit much.

Lack of torque at the upper rpm range hasn't been a problem for me. Usually I'm running end mills 3/16" and smaller in aluminum so no need for much torque.

Good luck with your retrofit project. Your thread has been a good read.

 

[COMachinist]

Hi PZ
Could post the numbers and the place where you bought the NGK bearings I want put ne bearings in and up grade to 2hp 3ph moto for better control on my rpm. I like to run a faster on the aluminum parts I make.
Thanks
CH

 

[phazertwo]

I ordered them for qualitybearingonline.com. 7206CTRSUMP3-NSK, and 7207CTRSUMP3-NSK. They are out of the UK, so I had to pay in lbs, but paypal handled the conversion for cheap.

I decided to go with them even thought there is probably someone closer that deals in good ol' $$$, but they were quite helpful while trying to find precision tapper roller bearings.

PZ

 

[phazertwo]

Well I got back from Moab Saturday afternoon and was back working on the mill last night!

First I got the VXB bearings out of there packaging and cleaned up. They are nicer than I first thought, which is fantastic.

Then it was time to load them up with the ISOFLEX. I'm pretty particular about the way that I pack bearings. I pack them from one side until the grease comes out the other side. Then I just smear it all over.

The 50g tube is just the right amount for the two bearings.

Then came the hard part. How to press them in with out pushing on them wrong. I found some press adapters from another project that worked just right. It's like $15 bucks on the Amazon.

The larger of the adapters worked great for the big bearing and the smaller for the smaller bearing.

Then I ground down the old cone race so it slipped in and out of the quill.

Coupled with my Harbor Freight 3/4" press adapter... I mean 3/4" drive socket set, it worked like a champ.

Don't forget to put the set screw / collet key in before you put it all together... It's a pain in the ass to do afterwords, ask me how I know...

For the smaller bearing I had to rely on the angular contact. I had to push on the inner race even though it was pressing against both races. Seemed to go just fine.

After that I set it up so I could tighten the spindle nut. It also allowed me to spin the whole setup, and man is it just SMOOTH!

None of the fingers on the spindle nut keeper were even close to lined up... of course. So I found this on the ol' Amazon, think it should keep the spindle nut tight.

https://www.amazon.com/gp/product/B00UHE3DHG/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Feels real good to have some progress after working on other stuff for the last few weeks. Next step is to try to get some mill time on my friends mill so I can make the motor plate. That's the last piece I need before I can get it choochin' again.

PZ

 

[phazertwo]

Well a month later and I finally have a very small update.

I ended up at my parents house for Independence Day, and was looking at my dads home brew CNC router and thought, why don't I make a temporary motor mount plate out of wood... Maybe it will work, maybe not, but hey it's what is holding me up at the moment and it' something to do.

My plan it to use this to make an identical motor plate out of 0.5" aluminum. I'm hoping it will last long enough to get it done... or maybe the motor will fall off... I guess we'll find out.

PZ

 

[phazertwo]

Got an incredibly small amount done yesterday. I mounted the motor to the wooden motor mount, and got it all attached to the mill. I will defiantly need to trim the casting, which I knew I was going to need to do. Unfourtunatly I ordered the largest pulley that I could fit in the head, which was 140mm... With the belt on it only gives me ~2mm/side of clearance. I am going to have to step that down to a 132mm pulley to feel comfortable running it...

I'm very glad that I made the first motor mount out of wood. We'll call this one REV p1, the aluminum REV A will rotate the motor a bit to help get the electrical connections in a better spot, along with have some large holes to help get the belt on the back side of the pulley.

In case anyone was wondering why my progress has been slowed to a crawling pace... we are expecting our first kid at the end of October and I have been spending most of my time with house stuff getting ready for a half pint. That along with some crazy weather (wind/hail) that has caused damage to our house/vehicles I've been very tied up. HOPEFULLY I can get the mill back together and making parts before half pint shows up and my time in the shop takes a digger!

PZ

 

[phazertwo]

OH MAN!

Guess who showed up early!

Born 10/21/18 at 1:10am. Mom and baby both did great, and everyone is now home trying to figure out how this all works!

In preparation for the little man showing up, I cut down a big cottonwood tree that was dying in my front yard. We had to rig most of it out so we didn't hit the house, it was a ton of fun.

Those are just a few pictures of the 6hr time lapse we took... maybe some day I'll turn it into a vid.

Then I had to build a shed, which was much less fun, but it's done none the less. The shed is a big deal because it will allow more space in the garage, which hopefully will make it easier to work out there when I do actually get some time!!

In the mean time, I've been working in Fusion trying to get the new belt drive system finalized... Hoping to have that done soon so I can order parts and get the mill running again. We'll see how it goes.

PZ