[mrcodewiz]

The highlighted bearings are the ones that feel tight:

[Maglin]

Ok I did some searching and if it is indeed a 45x85x19 then this would be the bearing you would want to use in it's place. What is the numbers on the bearing and race you removed for this bearings location? You can get it's dimensions for it to ensure it's the correct size.

You have a PM coming. Instead of using up space here. I'll see if I can't help you out here.

[mrcodewiz]

Opps I pretty much messed it up. TY photomankc. I'm going to fix it.

mrcodewiz do you have a G0704 or a BF20 or PM20/25? Your second bearing is huge and not for a G0704. If you had to use a hammer to get it installed into the head you could have distorted the race (unlikely but possible) which would of course cause some issues.

Edit: Also that Nachi Bearing 45x85x19 isn't an AC bearing and it could be bound up with angular loads. I'm willing to bet it could be the root cause of the problem. Did your first motor go out shortly after you replaced the bearings?

First motor went out long before I replaced the spindle bearings. I didn't do the bearings until after the 2nd motor blew and I decided to go to a treadmill motor.

[ncdeftones]

Absolutely. I did that on both the X/Y and the Z. A tap would be faster though. I used a carbide insert bar from Shars. Worked great. I'll see if I can dig up the link at home.

I ordered a thread milling bit of MSC. I'm not sure if you are CNC'd already and/or if your software package supports thread milling, but if you choose your bit correctly you can machine a wide range of thread sizes & pitches in both Metric and UN using one single thread mill cutter.

[ncdeftones]

Someone earlier said to get stainless steel balls and that is not what you want. You want chrome steel,that is what comes in the ballscrew. They cost less too.

Hum....yes you are correct about the chrome steel. Cheaper...well on this Bal-tec place not quite...$.24 ea for 250+ and then the price doesn't drop again unless you order 5000+ at which point you get them for $.11 ea. I definitely do not want to have to spend $550 to get them at a decent per unit cost. Enough for 2 axis would still cost about $45 and 3 axis about $60.

Anyone know any other place to get these?

[hoss2006]

So this morning I pulled the quill out of the head in order to test the amp draw without the spindle or spindle bearings being factored in but with the rest of the drive train intact. That means all the geas as well as the quill sleeve and bearings.

For a little more background, it was colder this morning than it was when I ran my test yesterday. It had been in the 40s all day yesterday and dropped to the 20s last night and was maybe 30 this morning. I mention that because that quill sleeve seems much harder to turn when its cold.

I turned it on in high gear to about 350 RPM and it was already at 3.8 to 4 Amps. Turning it up past 400 RPM made it climb to 7 or 8 Amps. This is with no load and not even a spindle.

I can't imagine that the speed controller would have any effect on the draw would it? It is just pushing voltage to the motor. So it either has something to do with the friction in the drive train (maybe those bearings) or this motor is also no good.

Grizzly only specs ambient temperatures of 41-104 F for running the mill.
The grease in the bearings is going to be very stiff at 20-30 degrees and of course will put more load on the motor.
You need to let the mill warm up at low speed before attempting to run it when it's so cold.
You gotta expect differences when comparing a frozen mills performance to one that
sits in a 70 degree shop.
Hoss

[mrcodewiz]

Makes sense. I actually did warm it up when I first had the fuse blowing issue but I will re-run my tests tonight and let it run for 10 or 15 minutes first.

I guess I am just used to the X2. It doesn't seem to be affected by the cold as I use it year round without issue.

As a side note - I am not sure I trust the Grizzly parts manual. I was going to buy those bearings just in case but it lists that lower bearing as an AC which is different than the optimums and it lists the upper as a double shielded even though it appears to be a rubber shielded.

[hoss2006]

The lower head bearing is a 6007rs on mine (sealed deep groove) 35x62x14, same thing that's on an X2.
http://bearingsdirect.com/store/inde...t_detail&p=193
definitely not an AC.
Hoss

[mrcodewiz]

The lower head bearing is a 6007rs on mine (sealed deep groove) 35x62x14, same thing that's on an X2.
http://bearingsdirect.com/store/inde...t_detail&p=193
definitely not an AC.
Hoss

Yeah, that is what I figured. The parts list calls it out as a 7007 which appears to be an AC. I didn't even realize that it was the same as the X2 - I have spares for that.

[mrcodewiz]

Well maybe it is just the cold temps. I didn't have time to do an actual cutting test but I started the mill up in high and set it to 1000 RPM. It immediately showed 6.5 Amps being drawn. I let it run for about 25 or 30 minutes and it was down to just over 2 amps which seems more in the realm of acceptable. It was also much easier to turn by hand at that point.

I don't have a heated shop - Am I just going to have to let it run for 20 or 30 minutes first when I want to use it and it is below 40 out?

[hoss2006]

Any thought of using a treadmill controller for the treadmill motor?
Good idea to get a matched set.
I just picked up one on ebay for mine for $25, it retails for $150.
Shouldn't have any worries that they'll work together.
Hoss

[hoss2006]

Well maybe it is just the cold temps. I didn't have time to do an actual cutting test but I started the mill up in high and set it to 1000 RPM. It immediately showed 6.5 Amps being drawn. I let it run for about 25 or 30 minutes and it was down to just over 2 amps which seems more in the realm of acceptable. It was also much easier to turn by hand at that point.

I don't have a heated shop - Am I just going to have to let it run for 20 or 30 minutes first when I want to use it and it is below 40 out?

Gonna be 60 degrees here friday so this worry should be behind you soon too.
Maybe think of adding heat to your shop next year.
Don't know how you could stand working when it's below 40 let alone the mill.
Hoss

[mrcodewiz]

Gonna be 60 degrees here friday so this worry should be behind you soon too.
Maybe think of adding heat to your shop next year.
Don't know how you could stand working when it's below 40 let alone the mill.
Hoss

Well, I have a propane heater but i just use it in bursts. Its good to heat up the air and take the chill off but it doesn't really warm the machines up.

I would love to add heat but thats far off.

[hoss2006]

Just tossing out the idea of looking into a thermal blanket or tape.
They use them in cold climates to keep engines, batteries and other equipment warm.
Maybe put one on a timer if you go out in the shop at a fairly regular time.
It'll be toasty and ready to roll when you are.
Hoss

[Maglin]

Yeah, that is what I figured. The parts list calls it out as a 7007 which appears to be an AC. I didn't even realize that it was the same as the X2 - I have spares for that.

FYI 7007 is a PN for a regular ball bearing. A 7007B or C ect. would be an AC bearing. The letter after the bearing spec number is the angle of the contact area.

[mrcodewiz]

Ah, I was just looking on VXB's site and didn't see any 7007 that wasn't an AC.

I think I am going to move ahead with building an enclosure that can be heated. I was sort of holding off on the enclosure until I thought everything else was completely done but this is another good reason to build it.

[paulsv]

Just a tip for those of you who, like me, read the comments a week or two ago on this forum about the Shars Co-Ax indicator set for $39.00. I ordered one and tried it out last night, and it wobbles like a drunk on a tightrope. Kind of funny to watch, actually. You can actually see the whole body wobbling in the spindle when you turn the spindle on, and the closest you can get to a zero reading is about .010 or .015 on either side of zero. At $39, it's hardly worth returning, so I'll take it apart and see if I can true things up with a tool post grinder on the lathe.

[ncdeftones]

I'm not an electric motor technician, so could someone fill me in on why and what part of an electric motor generates the most heat? From what I understand there is no current flowing in the center black body that has the magnets, so why does it get so hot? The top that has the brushes and armature doesn't get all that hot, but the side gets so hot I can barely keep my hand on it.

I've even tried mounting a 12v PC fan on top of the motor to provide even better cooling, but the air coming out is barely warm at all, yet the sides will about burn me. It also seems the motor can run for a pretty good while and not have much heat at all and then in a matter of a few minutes the temps seem to spike up.

Hoss how is it you can run dog poop out of yours and have never had a problem one with the motor? I'm running 1/2" end mill ~1200 rpm @ sub 14 ipm @ .125 doc. The bit never even smokes the WD40 I spray on the work piece so I don't think I'm exactly pushing the machine very hard.

I'm finishing the piece I'm working on right now and then I'm concentrating on getting this dang thing to belt drive. This stock motor has got to go before I pull out my AR15 and unload 30 rds on the mill.

[photomankc]

I have a theory that there are some of us for whom every factory reserves the worst unit for. Our names are known and circulated and when we order something that everyone else has fantastic luck with we get the one unit that falls apart. They laugh and chuckle as they ship it.

I have always had that luck. If I have a problem, its a weird one that nobody else in the history of the internet has seen. If I buy a great brand of Hard Drive then I can expect it to fail 10x earlier for me. I buy a lathe chuck, I get the one that was made Friday afternoon. It almost never fails. I laugh about it now but it does almost feel like a conspiracy at times.

I bought a group of chips for an electronics project once and nearly 50% of them would not function. I would never have believed it even possible but when tested as requested by the manufacturer they sure as heck tested bad. Something happened in transit to them. I'm like the reverse King Midas of ordering stuff.

Motors heat from two sources I know of. One, the effect of large current passing through the resistance in the coil wires. The energy lost in resistance is converted right to heat. At 90V to 180V and at 5 to 10amps even a tiny amount of resistance produces a lot of heat. Also magnetic changes cause heating - the faster the field is switching in relation to something the more it heats it. Electomagnetic coils can be used to heat steel to red hot in a few seconds.

[paulsv]

I have a theory that there are some of us for whom every factory reserves the worst unit for. Our names are known and circulated and when we order something that everyone else has fantastic luck with we get the one unit that falls apart. They laugh and chuckle as they ship it.

My name is right under yours on that list! With Shars, I think they may sell off their defective units on ebay under the "Discountmachine" name. In addition to the indicator, I ordered a 2 and 1/2" indexible face mill from them. It was half the price they listed it for on their Shars site. Problem was, the hole for mounting it to the arbor was too small. Luckily a minute on the lathe was able to fix that, and it now cuts beautifully.