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mcdanlj

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It seems that several folks here post about their new mill and the thread goes on for years, so hey why not do it on purpose? I'm in the middle of doing some other work to my shop, so it will be a few weeks before I really get to do anything interesting with the mill. But here's the initial report.

You know you have good friends when they enthusiastically offer to help move ~600 lbs of mill (PM-30MV) and ~300 lbs of bandsaw (PM-712G) into a basement shop! :angel:

While the mill face plate, PM site, and PM manual all list the top RPM in the low range as 1500 RPM, I saw max 1300 RPM in the low range during the break-in. In the high range, I did hit the advertised 3000RPM, and PM said that there are different pulley sizes now. That's probably good; it means more torque in the low range which is kind of the point of the low range. Just something to be aware of; I think it's a positive thing. :encourage:

Runout is about a thou (I'd estimate 8 tenths) measured both against the inside of the spindle and against the body of a mitotoyo edge finder in a collet. (For grins, I also indicated against the outside of the spindle above the flats, and that though meaningless was also about a thou.) I think that's about what's expected for a chinese mill, and if you want better you get taiwanese mill with japanese bearings? (I measured with a cheap DI, but it has indicated closely with my mitotoyo DTI.)

The mill runs so quiet!

Tech support has returned multiple emails quickly. :applause 2:

I have only minor gripes or surprises, no buyer's regret so far. I'll share the gripes, not to disparage PM, but just as information for the next buyer who happens to read this. If price were no object I would have bought a Taiwanese 3Ø + VFD!

It's pretty clear that PM expects the chip shield to be removed in practice. They ran packing tape across it so it's covered with tape residue. :rolleyes: Not sure what solvent would dissolve the tape residue but not the plastic. Limonene maybe? Does anyone actually leave the shield in place? (I like all the youtubers who say "Do as I say, not as I do—leave the shield in place even though I took mine off!") Similarly, does anyone actually screw that pretty blue shield back over the motor and drawbar between tool changes and speed range changes?

I am not in a position to anchor into my shop floor. I bought PM's stand for this mill with leveler pads as they were advertised to eliminate the need for anchoring, but it was too narrow and tippy, and too low for my comfort. I set the mill on a 2'x4' tool chest for now as a temporary measure, but while it is not nearly as bad as the stand it still wobbles a bit when I raise or lower the head. I like having drawers for tooling right below the mill though! The bench I got puts the table 45.5" off the floor (it's 37" tall itself) which is a little too high. I think I need to remove the casters from this or more likely a narrower tool chest, and build a sturdy frame around it that holds the bench and the mill and integrates the leveler pads. I do regret buying the stand, though if I were bolting it to the floor and wanted a low table for making it easier to lift heavy objects, it would probably be fine. (If anyone in the Raleigh NC area regrets not buying the stand, let me know, I might have a deal for you!) I'll share my mill stand design in the appropriate part of the forum, it's hardly PM-specific.

I was somewhat surprised that when I bought the X power feed with the mill, it shipped with trapezoidal stop way keys that didn't fit in the keyway and needed to be cut down. But it turns out I had a tool handy that could do a good job of cutting the keys down! ;) It was also missing a few M8x12 mounting screws that I didn't find matches for in my spare part bins, so PM is sending them.

There is paint overspray on the Z ways bearing surface halfway up the column. I have a sneaking suspicion this is one of those "china vs. taiwan" quality control issues, to which I also attribute the dings in the edge of the table surface (I think only cosmetic) and some tiny pitting on the table surface and Y bearing ways (ditto). PM recommends steel wool or scotch brite red for removing the overspray. Since scotch brite red has aluminum oxide in it, steel wool sounds like the gentler option. It turns out gentler means taking a long time, though! Given how far I got in about 15-20 minutes, I expect it to take an hour to really clean off.

A couple days with WD-40 wasn't enough to get the yellow stain from the rust-preventative hard grease out of the paint or off the front scale; I think it's effectively permanent. I'm a little scared to ask what's in that grease, and glad I was wearing nitrile gloves while removing it. :p

Just funny: the manual that comes with it calls it a "variable speed lathe"! :cool:
 

shooter123456

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It seems that several folks here post about their new mill and the thread goes on for years, so hey why not do it on purpose?
What starts as "I got a new thing!" becomes "Hey look what I did with my new thing!" and eventually "My new thing still works!" Its the natural progression.

Does anyone actually leave the shield in place? (I like all the youtubers who say "Do as I say, not as I do—leave the shield in place even though I took mine off!")
I found it wasn't possible to mill anything with the shield in place. You couldn't get an end mill to a workpiece without the shield running right into the vise. It was taken off before anything could be milled. I feel like it is a liability thing. If they put it on there and you take it off, then a chip flies into your eye and you try to sue PM, they can respond "He removed the safety features and used the machine in a way it wasn't meant to be used. His fault, not ours."

Similarly, does anyone actually screw that pretty blue shield back over the motor and drawbar between tool changes and speed range changes?
I think I put my machine in high speed range and left it there with the cover on. I didn't need to take the cover off to change tools though. Now I have an air cylinder blocking the way of it so it does not get used.

A couple days with WD-40 wasn't enough to get the yellow stain from the rust-preventative hard grease out of the paint or off the front scale; I think it's effectively permanent. I'm a little scared to ask what's in that grease, and glad I was wearing nitrile gloves while removing it. :p
That stuff was nasty... I tried WD-40, mineral spirits, and rubbing alcohol and it didn't budge. But it dissolved immediately with acetone, so that may be a way to go.

Congrats on the new machine though! I would love to see some pictures.
 

wrmiller

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Although the mill was smaller (PM-25), I had good success with putting it on a 40" toolbox. For many of the reasons you mention. :)

My solution to the toolbox stability issue was that I made four little screw jacks and put them on the corners of the box. Much more stable.
 

mcdanlj

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That stuff was nasty... I tried WD-40, mineral spirits, and rubbing alcohol and it didn't budge. But it dissolved immediately with acetone, so that may be a way to go.
Oh, I got the grease itself off by soaking with WD-40, some of it overnight. It's just that thte grease stained the paint and scale. (Here I was going to use this mill as a beautiful centerpiece on my thanksgiving table, and now the aesthetic is ruined! :p)

Congrats on the new machine though! I would love to see some pictures.
I had given up on the mill arriving any time soon and started a shop upfit that I expected to complete before the mill arrived. It was past time anyway for the upfit, so it was a good decision, but it means that the mill is in the middle of a mess I don't really want to post a picture of yet. I'll post when I have it mounted the way I want in a shop that's not in a mess of construction. :cower:

Although the mill was smaller (PM-25), I had good success with putting it on a 40" toolbox. For many of the reasons you mention. :)

My solution to the toolbox stability issue was that I made four little screw jacks and put them on the corners of the box. Much more stable.
The tool chest it is on right now is 46" wide and it's not working great; I don't think this particular chest is strong enough for very asymmetric loads, and it wiggles just cranking Z up and down. My plan is to put the 46" tool chest on rollers to my left as I face the mill, with the top available for work space, and then put a smaller tool chest under the mill in the rigid frame I designed with outrigger feet. Glad the screw jacks worked; that's basically what I'll have with the leveling feet that I bought from PM.

I think I could find a tool chest strong enough to mount the mill on directly, but it might cost more than the mill! :rolleyes:

I'm going to have more trouble with stability than a normal person because the reason I can't anchor the mill is that it's on a floating wood floor that is floating on a thin layer of rubber. Great for comfort, great for not breaking tools that drop, not so great for rock-firm stability.

This is my first experience with a mill this large, which is why I had poor intuition about what to order. That's why I wanted to share for the next inexperienced hobbyist.
 

mcdanlj

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The more I use the mill, the more I'm convinced that my stability problem is the layer of rubber in my floor, and it's not a problem with my cabinet. It really only bothers me when I'm cranking Z. Taking a break from upfitting my shop, I ordered a motor with a 4-groove pulley and a 200J4 belt and I'm planning to use my lathe to cut 4 grooves in the crank wheel to turn it (pun intended) into a 4 7/8" J4 pulley, or cut a new (larger?) crank wheel c̅ pulley from some scrap toolplate I have sitting around. The existing crank wheel will give me almost 5:1 ratio. I don't know whether this motor will have enough torque; I didn't do anything smart like measuring the torque it takes to lift the head. If I need a larger wheel, I might need to order a larger belt, but about $6 for the belt is cheap enough.

I'll still have manual Z adjustment ability if I want it (with a little extra work turning the motor unless I make a way to disengage it physically, which is probably not worth the effort).

I plan to run it through an ON-OFF-ON DPDT switch for forward / free run / reverse to enable hand cranking, and at least eventually I'll probably end up making my own motor controller for it. I think I have all the electronic components I would need for a simple PWM controller, and that wouldn't take too long.
 

mcdanlj

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I finally measured: 10lb max force at 2" (the crank handle) to raise the head, so 20 in/lbs. I measured stalling torque on that motor, which arrived today, at 1.0 lb at 9 inches at 24V, so 1/9 in/lb — call it 0.1 in/lb to be safe. That would require roughly 200:1 advantage. This doesn't look like a winner of an idea. Looks like that motor will end up used for something else some day! Back to square one. (I had a more powerful DC motor salvaged from a broken lawn tool but it went missing and I'm very afraid another family member inadvertently disposed of it.)

Also, the grooves on the pulley on this motor are about 1.6mm apart, so definitely not J profile 3/32 belt. I don't know what belt they were designed for, but not any of the gates profiles. That would make things more complicated.

If I make a new larger crank wheel, I'll have to offset it away from the column to avoid interfering with the upper Z gib lock.
 

mcdanlj

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Found the missing motor while looking for something else. It's a DC motor from a roughly 15-year old version of this hedge trimmer, but it ran off of 120V AC through a bridge rectifier, so I can preserve that — it even has a braking function shorting out the motor leads when it isn't running. I can probably run it through a dimmer switch to change speed, though I haven't tried that yet.

It has a reduction gear in it that I can and should use; the gear housing incorporates one of the spindle bearings for the motor anyway. I'll need to make a mount that holds the driven gear in the housing with a hole for a pulley, probably for J4 belt. I'm able to back-drive it, so I want to preserve the ability to do small height tweaks by hand with a crank, with a belt behind the crank wheel to turn it with the motor. I'll see how that works, and if it works well I'll post pictures.
 

mcdanlj

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Almost finished making a new Z crank with a J4 pulley on the back today. Only two things left: cutting the 4 belt slots, and making the tapped hole for the crank handle. I carefully ground a form tool for J4 slots, and then found that I can't use it in my current setup because the tool holder will hit the jaws on the chuck. So now I'm trying to think through setups to see whether I need to grind a new tool (on the other end of the same blank, of course) or if I can find another setup.
 

mcdanlj

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Ground a new Gates J form tool (my best guess; I didn't measure anything) at 45⁰ on the other end of the blank, which got the toolholder out of the way of the chuck jaws.

The crank screw is M10x1.5. At least on my unit, the crank handle was aligned with the keyway, and I did the same with my replacement.

I now have a crank that sticks out just a little bit further than the old one, and uses that room for a belt on the back. It still has the index wheel and works by hand. I sanded it with a medium grit sandpaper for a satin finish in case I'm turning the wheel itself for fine adjustment. (Also, that way I didn't stress about trying to attain a mirror finish on cast aluminum!)

DSC_0730.JPG

Here's the face:
DSC_0731.JPG

I made it all from scrap. I used 1.25" aluminum rod (clearly used to be a roller of some sort) for the driven pulley in the middle, and cast plate offcut for the wheel. I bored a 0.4" hole in the plate to 1.25". I accidentally made it too loose, so I used gel cyanoacrylate glue to fix it in place. Then I bored out the other side into the 1.25" rod far enough to be able to use the existing washer and nut, and bored into the plate enough to reach the nut. You can see the interface between the two kinds of aluminum on the outer of the two inset faces.

At one point, the glue lost its grip during an interrupted cut (from roughing the wheel on my bandsaw in vertical mode). I thought I was in a real mess and wasn't sure how it was going to work, but the glue seemed to re-harden and work. So far so good. It won't be under load when using power, only when using the hand crank. Fingers crossed!

I haven't made the other end yet, so the belt is dangling loose... But this shows where it will go. I'll make and mount motor and drive pulley on the back of the column.

DSC_0732.JPG

To guide the tap, I took an small old broken drill bit shaft, and ground the back of it to a dull point on my grinding wheel. Then I chucked it into the mill and kept some light downforce on it into the dimple in the top of the tap while starting the threads, for the first few turns. Made it easy to keep the tap aligned vertically with the hole I had just drilled!
 
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mcdanlj

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The nylon locking ring in the nut didn't quite engage the threads, so I bored out another 0.1" and now the nut now tightens securely:

DSC_0743.JPG

While I was at it, I added some bevels. The innermost bevel makes threading the nut more comfortable. The large outer bevel just makes it a slightly better visual match for the other hand cranks and looks a little better. I didn't measure any of the bevels, just eyeballed them.

Here's what the profile on the back looks like:

DSC_0739.JPG
The upper part is just a copy of the shaft in the back of the existing crank, and the index wheel fits over it with the spring in the groove. The bottom part is slightly longer than it really needs to be and has my attempt at a J4-like profile cut into it. (Probably it will shred the belt and I'll start over after grinding a new attempt at a form tool.) The dimensions aren't critical.
 

Landmark

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I am so happy to find a PM30MV owner posting about their experience with this mill. I am one click away from ordering one and will also be sharing my experience.

Your power z-axis build looks great. I wonder is you are planning to do a CNC conversion on this mill in the future. I have a Grizzly G0762 mill that I am going to leave for manual machining and hope to do a conversion on the PM30MV.

Thanks for sharing!

Mark
 

mcdanlj

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@Landmark I'm about to start my project to CNC my first mill, a HF mini-mill. I could see someday if my appetite for this hobby keeps increasing that I would someday buy a larger mill and CNC the PM-30MV, but for now no such plans. :)
 
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