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Another PM940-CNC-VS Thread...

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Rickwjenn

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Congrats! Nice update and pix! You should be very proud and you are a fine american taking such good care of your family and property. That tree is one amazing job. Bet you notice "big sky" for the next few weeks!

The shed looks great. What all is going in it?

Fusion360 is great and I am just scratching surface of learning it.
 

phazertwo

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Congrats! Nice update and pix! You should be very proud and you are a fine american taking such good care of your family and property. That tree is one amazing job. Bet you notice "big sky" for the next few weeks!

The shed looks great. What all is going in it?

Fusion360 is great and I am just scratching surface of learning it.
Wow, thanks!

Well I had a shed that I tore down the same day we removed the tree. It was junk, the floor was collapsing and there was only a small man door to get into it. This one is double the size, and has the double door at the front (I increased the door height from what the plans called for). This one fits our small side x side (pioneer 500) all our camping gear, all the outdoor power equipment and some other odds and ends, and its all locked up!

PZ
 

phazertwo

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Slight update... I had some friends come over Friday night to help me move some heavy stuff around in the garage. Not sure if I ever mentioned that I have a bulldozer project in my garage, but I do... and all of the parts that come off of it are too heavy for me to move by myself, which is why I needed all the friends. We got done moving dozer parts faster than I thought we would, so we took some time to get the mill on it's new feet!

These are just the feet you can buy from PM. They are nicer than I expected, and the mill is now level and all 4 feet are firmly planted. Before it was not level and I had some scrap metal wedged under one corner to keep it from "floating." With out having any machine time on them, I highly recommend them. I couldn't find anything I liked for nearly the cost of these, so they seem to be a great value. They have a fair bit of rubber on them, so I think they will dampen quite well... I'll try to remember to post more comments when I run the machine again.
IMG_20181102_202922.jpg

Parts used:
PM Leveling Pad

PZ
 

bretthl

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Anyone know why PM stopped selling the CNC version of the 940?
 

phazertwo

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Anyone know why PM stopped selling the CNC version of the 940?
I didn't know that they had? It was never advertised on their site, you had to call. Don't be afraid to give them a call or drop them an email, SUPER nice people, ready and willing to help!

PZ
 

smartin733

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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[/QUOTE]

Just curious about the precision tapered roller bearings... How much were those going to cost compared to the angular contact bearings? I've been thinking about purchasing the PM-940 or the 833T and doing a cnc upgrade. I can't seem to find much (at least easily) about precision tapered roller bearings.

Thanks,
Shane
 

TomS

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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
Just curious about the precision tapered roller bearings... How much were those going to cost compared to the angular contact bearings? I've been thinking about purchasing the PM-940 or the 833T and doing a cnc upgrade. I can't seem to find much (at least easily) about precision tapered roller bearings.

Thanks,
Shane[/QUOTE]

Here's some tapered roller bearing info to get you started. https://www.timken.com/pdf/5722_Precision Tapered Roller Bearings.pdf
 

phazertwo

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Just curious about the precision tapered roller bearings... How much were those going to cost compared to the angular contact bearings? I've been thinking about purchasing the PM-940 or the 833T and doing a cnc upgrade. I can't seem to find much (at least easily) about precision tapered roller bearings.

Thanks,
Shane
The link provided by TomS has some great information, and is pretty much where I started when researching taper roller bearings. Timken has some great information on them, and I was even able to find the part numbers that I needed... however NO ONE can get them. Which is really unfortunate because a precision taper roller bearing would be better than AC bearings just because they have a much higher load capacity...

Anyway, I'm pretty good at the ol' internetz, and I used some of my contacts from my industrial maintenance days to find some. The only thing I could come up with are off brand C3 precision (just "3" in the table in that link TomS provided), in my opinion, you need "0" precision or better. The factory spindle bearings are taper roller bearings rated at C3, but you have to take that with a big shot of Chinese salt. Mine were not packed with grease properly, and the bearings met an early end. If you do get a 940 (I would check an 833-T as well) pull the spindle apart before you fire it up and pack those bearings properly.

If you happen to find some taper roller bearings "0" or "00" precision let us know. Some of the places I went had them in their system, but a week after I ordered they canceled the order saying the couldn't actually get them.

PZ
 

phazertwo

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Alright, I'm tired of dealing with pics with broken links, especially here on Hobby Machinist since you cannot edit old posts... So I'm giving a new hosting service a try (Flickr).

This week I received new pulleys for the belt drive. Motor pulley will be 132mm and spindle will be a 90mm. This gives me 1.466:1 ratio, so I should get about 5000 rpm out of the original motor, and 10250rpm with my new motor... but more to come on that later.

I ordered the pulleys from Ametric again, except that I ordered the wrong bushing for the spindle (ordered a 24mm bore instead of a 28mm) lucky for me Whistler Bearing had one in stock, so I took a long lunch and grabbed it yesterday.


Also had a friend with a lathe turn out a quick spacer so I can ensure proper preload on the spindle bearings.


Hoping that I get some time this weekend and next week to get everything assembled *correctly*, tram, and fire it up! Then I can start some fun with the new motor!

PZ
 

phazertwo

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Well, I've got a fair bit of work done on the mill that last few weeks. I have only been working in hour long chunks here and there, but it's something. I got the whole thing assembled, trammed and and tested... I didn't take my normal number of pics because of time constraints... but I did get a shot of how ghetto this thing is. The temporary motor mount didn't work out as well as expected, so I had to clamp it down. It still has bolts on the back side of the motor, and I had to hit it pretty hard with a dead blow to make it move.
IMG_20181226_221207 by Phazer Two, on Flickr

It's UGLY and I'm not proud of it... but it works, and it's pretty dang quite (click for vid).
VID_20181227_184401 by Phazer Two, on Flickr

Anyway, I have to make one part to mount the new motor with a legit motor mount, and I think I've decided I'm going to do it with this wood pile of crap. Even if the motor mount slips, I just loose tension on the belt which means I break a tool... Nothing catastrophic. I took the time to tram the machine to the best of my measuring abilities. To get it right I had to shim the head. Using the table to remove the head works fantastic, especially if you set your zero right before you unbolt the head!
IMG_20190101_133439 by Phazer Two, on Flickr

I've been watching Ebay close for deals on upgrade parts, I scored a few things, one of which is this massive air cylinder. Its a 5" bore x 4" stroke two stage. I think I'm going to disassemble it and try to get it down to 2" stroke so it's not so dang tall. $120. It's next to my new compressor for size reference. The new compressor is a 150psi unit, compared to my current worn out 120psi comp... so I should be able to get well over 5k lbs out of this cylinder.
IMG_20190107_175651 by Phazer Two, on Flickr

I changed the stepper drives from 1600 steps/rev to 2000 steps/rev but have not had time to tune it. I have a small list of things I need to do before building the motor mount:
  • Load the latest flavor of Centroid software
  • Tune for 2k steps/rev
  • Install mist coolant Rev B. (not necessary, but I would like to test it out. More on this later)
Exciting stuff...
PZ
 

phazertwo

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I missed one thing that I needed to get done... I need some kind of containment. Since we had the kiddo, we decided that my wife should park inside, so she doesn't have to walk out on our steep(ish) driveway when it snows. Also, she doesn't have to scrap windows, which saves her some time in the AM and you need every second you can get trying to get this fat baby out the door. Anyway, can't be shooting chips all over her car, and need to try to keep them from getting into the house.

So, I summoned my inner Martha Stewart and made it happen...
IMG_20190113_150342 by Phazer Two, on Flickr

I have been thinking about doing this for a while, but couldn't decided if it was going to be too hodge podge. Turned out to be fantastic! It contained chips so they are only on the floor below the mill, so no more mess all over the garage. Another big plus is that it makes cleaning up much faster. The curtain rings are snap on things that I can get on and off pretty quick, so I can move it all out of the way pretty fast if I need too. When it's closed the two shower curtains meet right in the middle in front. Super happy with it. If you're looking for budget containment, I think this cost me $45-$50 all said and done.

I also got Centroid CNC12 updated, and tuned in for 2k steps/rev. I was able to tune it pretty well, I think it's actually better than last time, however it makes me want to go to 4000 steps/rev. I feel like that would make it even better/smoother.

After the curtain was up and the machine was tuned, it was time to make a simple test part. I just grabbed some scrap I had laying around and modeled up some features to measure.
IMG_20190113_171937 by Phazer Two, on Flickr

Everything came out great. I was taking it very easy because of the wood motor mount and all, so I ran it at about 50% speed to start. However halfway though it was doing so well I bumped it back to 100% and it just sang. Everything is really working well together, which feels really good. Now I just need to get my dang mist coolant running more consistently.... that should be next! Soon I will be cutting my new motor mount!

Parts used:
PZ
 

Firstgear

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Why is this unit or any other unit for CNC not offered anymore by PM?
 

phazertwo

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I don't think they ever offered any CNC units on their new site, and their old site didn't offer the 940CNC. You have to call or email them (I emailed).

If you have not contacted PM, I highly suggest you do. Matt is fantastic to deal with, and responds very fast. If I hadn't emailed him I would have ordered the wrong machine for sure.

PZ
 

fritts

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I actually just ordered and received one of the last two 940 CNC's they have. Also got a good deal on it as well. If you are still looking I would suggest calling them. I think the problems with Mach3 and the nmotion card pushed the cnc version out. Based on what he said it sounds like they may be looking at bringing it back later with a different control.
 

Firstgear

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makes sense...I sent an email inquiring.....
 
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