New PM-728-VT Setup

[bburns0909]

Well, the 728-VT finally arrived this last week. Thanks to all who chimed in on the decision thread > here. I ended up getting the mill, base, DRO install, Ultra Precision 0-.5" chuck, clamping kit and power x-axis feed. FYI...it's going to stay manual. No CNC for me. The packaged arrived without issue. Everything was packed very well. SAIA delivered and they rolled it right into the garage with no problems. Unloading the mill and getting onto the base by myself was a little challenging, but not as bad as I thought it would be. Setup was very straightforward with only a few hiccups. Here's what I ran into during the setup:

• The bolts used to attach the power feed to the table were too short. I had to cut some 1.5" bolts down a little to fit within the table end tray and tighten up on the table edge.
• The thing didn't come with a manual. Not a big deal cause you can get it online, but still.
• I checked the runout on the drill chuck and it was something like .0018" which is a higher than advertised, but only tried it once. I'll try again later to see if it was the setup.
• The DRO comes with a "grounding kit" (a 2' wire). Where am I supposed to hook the ground into? The instructions said nothing other than it was a "earth ground". Hooking that up to an actual earth ground is going to be a PITA. Is that necessary or can I just tie into the machine body somewhere? I have the DRO and the machine plugged into two separate panels.
• The quill has a noticeable "cog" to it when turned by hand and at very low speeds. I was anticipating it to free spin when the motor is off, but that's not the case. Feels like motor magnets are pulling on and off. It smooths out fine at high speeds. Maybe this is normal for this type of motor?

I can't wait to get to some projects. On the list so far is...
- Copper soft jaws for the vise
- Mini hold down fixture plate & clamps (Lipton style)
- T-nuts for a Vertex HV-6 rotary table

How the package arrived:

I used a 1-ton shop crane (HF) to lift it. It handled it fine.

Fully Assembled:

Tramming it in. I got the X-axis dead nuts very quickly with this setup. The Y-Axis has about .001" forward nod just with a quick check. I might mess with that later, but left it alone for now.

First chips: Using a roughing end mill, I went to town on a chunk of 6061. The mill makes pretty good blocks of metal so far from what I can tell.

Cheers!

 

[markba633csi]

You'll want to see if the DRO is stable with the spindle motor running. You may want to power both from the same outlet or separate ones. If you have problems with the separate outlets try them on the same one.
The ground they refer to is most likely the machine itself, which should have a ground through the power cord to your house ground.
-Mark

 

[AlanB]

Cogging when off is pretty normal for BLDC motors. Strong magnets and iron and all. I doubt if they optimize the designs to minimize cogging. They could, but it tends to cost and/or affect some other parameters.

 

[bburns0909]

You'll want to see if the DRO is stable with the spindle motor running. You may want to power both from the same outlet or separate ones. If you have problems with the separate outlets try them on the same one.
The ground they refer to is most likely the machine itself, which should have a ground through the power cord to your house ground.
-Mark

I grounded to the machine itself like you mention. I don't see any issue with the DRO moving, fluttering or anything with the spindle running. I'll just keep an eye on it for now. Seems to be working fine.

 

[bburns0909]

Cogging when off is pretty normal for BLDC motors. Strong magnets and iron and all. I doubt if they optimize the designs to minimize cogging. They could, but it tends to cost and/or affect some other parameters.

I guess for a machine like this it could be considered a "feature" since there is no spindle brake. Helps with holding the indicator still.

 

[Just for fun]

Congratulations, it's a fine looking machine.

Tim

 

[6061T6]

One interesting note about the mill stand: The levelers use a pretty non standard thread -- 1/2" 12 TPI Whitworth! I would have never guessed that this thread is a popular one in China. which apparently it is.
I want to replace the levelers with leveling casters (rated to 650 lbs each so they are heavy duty). I guess I will have to drill them out and use helicoils of 1/2 13" TPI.

 

[bburns0909]

One interesting note about the mill stand: The levelers use a pretty non standard thread -- 1/2" 12 TPI Whitworth! I would have never guessed that this thread is a popular one in China. which apparently it is.
I want to replace the levelers with leveling casters (rated to 650 lbs each so they are heavy duty). I guess I will have to drill them out and use helicoils of 1/2 13" TPI.

What interesting about the whole machine is that nearly all the fastener threads are imperial, but the heads of them are metric sized. I’ve never seen “hybrid” fasteners before.

 

[Genghis6400]

@bburns0909 congrats on a nice set up! I got a question regarding the quill fine feeding. Does the quill fine feed on your 728 feel smooth when you engage it? I just got mine today and upon inspection I find that the my quill fine feeding feels kind of clumsy and not smooth at all. I have locked the coarse feed in all the way to engage the fine feed feature. Hoping you could shed some lights on this matter. Thank you in advance

 

[bburns0909]

@bburns0909 congrats on a nice set up! I got a question regarding the quill fine feeding. Does the quill fine feed on your 728 feel smooth when you engage it? I just got mine today and upon inspection I find that the my quill fine feeding feels kind of clumsy and not smooth at all. I have locked the coarse feed in all the way to engage the fine feed feature. Hoping you could shed some lights on this matter. Thank you in advance

I honestly haven't used the fine feed much yet, but when I engaged it just now it felt smooth to me running up and down. Now the regular quill feed is clunky for sure, but the fine feed seems ok.