Chris' G0704 build

[ChrisAttebery]

The problem is that the bearing journals on the spindle are undersized already. The bearings are a slip fit onto the shaft. Any grinding I do is going to make them smaller. I'd have to turn them undersize and sleeve them. I also thought about grinding the taper in place on the machine. In the end I decided that since a new spindle is only $90 that I'd prefer to start with a good spindle. That also allows me to keep the mill up and running since I use it on a regular basis for my business.

I may try to rebuild the old spindle once I get the new on in place.

You've got a lathe. Build yourself a tool post grinder instead of buying another spindle. Grind the bearing bores and taper in to spec. You'll learn another skill in the process. If you get it worng you can always order another spindle or do both. order one to run on and rebuild the other.

[ChrisAttebery]

Well, my motor just went up in smoke. I got 7 years of hard use out of it. I was milling some steel, went into the house for a bit, came out to check on the machine and I could smell burnt electronics. It was still running. Then right when I walked up to it the breaker for the spindle tripped. The motor was over 250F. I let it cool down but it sounds like something is shorted out in the motor.

This isn't good. I bought the motor as a close out from PM. I doubt they have a replacement. I'm not sure where else I'll be able to find a 1100W 4200rpm DC motor. Not only that but I'll have to machine a new mount and pulley.

[ChrisAttebery]

Uggg, It gets worse. I installed my original 750W motor this morning. I figured that I could get by with it for a little while. It sounds bad. Like low power and bad bearings bad.

I'm leaning towards a 2HP AC motor and vector drive as the replacement. I just need to figure out which ones. I'll have to cobble a temporary mount together until I can get the machine back up and running.

[ChrisAttebery]

I went ahead and ordered a motor and VFD from Automation Direct. I went with the MTRP-002-3BD36 2hp, 3600rpm motor and the WEG Electric CFW300 series vector drive. My DC motor was 4500 rpm so using to the 3600 rpm motor with 25% overdrive should give me the same RPM range and more power available.

[CL_MotoTech]

That's a nice looking setup for a very reasonable price. I spent way more, and while i got more motor, it's probably overkill.

[ChrisAttebery]

Thanks. I looked at a bunch of the old threads here to see what everyone had installed. The motor is going to be a tight squeeze but it should fit. I briefly looked at the 2200W BLDC kit that Automation Tech sells. The motor is a lot smaller and probably would have been easier to mount but it's also $300 more.

[dazp1976]

I'll be going for a 1.8kw 3000rpm servo for my PM25 clone (belt driven, 2 spd version).
All I need then is for someone to turn me out a larger replacement pulley for it
Want to get it overdriven (still 2 spd) to about 3000rpm & 6000rpm at the spindle.
This should still give me the same torque as I have now but double the speed.

[ChrisAttebery]

Having a 6K+ top RPM is a game changer.

[ChrisAttebery]

I rebored my pulley from 12mm to .626". I used a sharpened piece of HRS to a key slot into it using my lathe.

[CL_MotoTech]

Yes, 6k on these machines is pretty good. I've run my spindle over driven as high as 8, the problem I ran into was getting the spindle and Belleville stack ballanced at 8k. So i've gone back to 1:1 and stick to 6k. If the machine weighed four times what it does the balance of the spindle wouldn't be so important, but as is, getting those belleville and drawbar really nice and smooth has been tough at 8k. I am using a 2.2kw BLDC with VFD that I imported from Taiwan and I am extremely pleased with it, I had a smaller unit by the same company before, and I just really like their setup so I was willing to pay extra for to import myself. I sent AT a message about the BLDC they sell asking if the rating was peak or continuous and never heard back, I decide to do what I was comfortable with. The motor I imported is 2.2kw continuous and up to 4kw peak. Plenty of power for a G0704... I'm now breaking end mills instead of stalling the spindle.

Anyways, keep up the great work Chris. It's always fun to watch people work on bench top machines and get awesome results.

[ChrisAttebery]

I’m in a tight spot. I don’t have a motor for the mill so I can’t machine a new mount. I decided to model the top of the machine and see what I could come up with. I realized that if I turn the motor 45 degrees that the bolts will clear the outside of the head. I made a couple plates from 3/16” steel on my drill press to mount to the head and turned a couple spacers out of 1” CRS on the lathe. This will move the motor 1” father back than the 1100W motor but it will still clear the column but about 1/4”.

[ChrisAttebery]

I pulled the controller box out this morning and removed the KBIC-225 drive I had used for the DC motor. The drive was clearly damaged. It's a good thing I didn't try to reuse it.

I got the top front corner of the enclosure cleared to mount the VFD. There's a hole 7.5"t x 6"w x 8-9"d. The drive is only 6.75"t x 2.75"w x 4.75"d. I'll have to wait until the machine is up and running to cut a hole in the face for the drive though.

[ChrisAttebery]

I received my shipment from Automation Direct yesterday. They shipped everything FedEx Overnight. That was a nice bonus.


I was able to get the VFD wired up to the controller and motor. Programmed the VFD and was able to start the motor from Mach3.

I got the pulley fitted. The key slot was a PITA and needed to be filed about a dozen times.

Here’s a side by side picture with the new motor and the 1100w motor. It’s roughly twice the size.

[ChrisAttebery]

I programmed the VFD to give the motor a 4500rpm top speed so that it matches the 1100w motor it's replacing. That way I can reuse all of my G code.

The belts should be here this afternoon. I need to grab a couple 3/8-16 x 3" SHCS screws from the hardware store.

[CL_MotoTech]

[ChrisAttebery]

" So today we've got the Binford Mill-a-matic 2000. Arrggg, arggg, arrgg..."

[ChrisAttebery]

I got the machine put back together and started a batch of parts yesterday afternoon. I took it easy on the first part but after that I went right back to the speeds and feeds I used with the 1100w motor.

Some observations:
1. The motor is quiet below 3500 rpm. As in with hearing protection it’s hard to hear it. Above 3500 rpm the fan is the dominant sound. It isn’t bad though. It’s kind of a low woosh sound.

2. I set the accel and deccel to 1 second each. I immediately noticed how much quicker the spindle ramps up and down. No more waiting for the spindle to stop before I change tools.

3. I had some parts that I started with the old motor and the finish seems to be better now. I think the old motor may have been struggling for a while.

4. After an hour of running non stop the motor was only about 25 degrees warmer than ambient. The old motor would have been 70-80 degrees over ambient.

5. Even though I have more power I don’t think I can push the machine any harder. I tried increasing the feed rate on one of my roughing cuts and I could hear the machine start to chatter and vibration levels increase. I think 1.5 cubic inches per minute in aluminum is about the limit for these machines. They just aren’t stiff enough to handle more than that. One exception is drilling. I had limited myself to 1/4” and below with the old motor and high speed belt drive. I should be able to push 3/8”-1/2” drills in the high speed setting now since the motor has constant torque down to 1350 rpm at the spindle.

[CL_MotoTech]

I regularly run 6000 rpm, .5 DOC, .15 WOC, .003IPT, with 3 flutes in 6061 while roughing. Feed rate is 54ipm for that. Unless I am doing the math wrong (this isn't a piece of math I do often), that gives me 3.4 in3/min. It's buttery smooth and the spindle seems to be barely working. I've accidentally pushed that as deep as .65 but things were marginal. Getting everything good and tight seems to have been what allowed me to jump from like .25 DOC up to the bigger numbers. I bought some 60 degree helix .375" end mills that I am going to try as well, I'm hoping to flex the machine less and achieve straighter walls with deeper engagement.

[ChrisAttebery]

When I push my machine past 1.5 in/min I notice that the Y axis seems to chatter, X isn't bad. My ball screws only have a single nut and I wonder if that is the problem or if the Y axis just needs to be freshened up. My machine is almost 8 years old now and I've put hundreds of hours on it. I could try adjusting the gibbs too. It's been a while since I've done any adjustments to them.

[dazp1976]

I

Looks tidy.
I also want mine a bit faster.
Issue I've got is I find the quill pretty useful and want to keep it working as is.

I've just had the idea of bolting a small 3rd pulley section on top of the stock 2 spd spindle pulley. Basically around the drawbar cap. (making it 3spd technically).
Then make a taller motor mount and the stock motor pulley will end up raised to be able to incorporate use of the new smaller one.
Just to see if it works. Would be nice if it does work for the moment.
I'll have to have a little look into it.

Otherwise the most likely way to go is a bigger motor pulley and wider motor mount unit.