New to me PM-45M CNC runout question

[hax0red]

Well I posted a few weeks ago about getting started on a G0704 or PM-727 conversion but after deciding I wanted the bigger PM-727M and realizing they were out of stock I decided to look locally and ran across a used PM-45M CNC about 20 minutes away. Ended up getting it for $4,500 with upgraded iMach 3 P1A-S Pendant, Shars vice, Haimer 3D Sensor, 20+ Tormach tool holders, collets, end mills, taps, Shars flycutter, DRO on Z axis and mister setup which will be welcome until I can build an enclosure to utilize the flood coolant setup the mill comes with.

It took me about two days to get everything in my garage cleaned and setup on the mill which left me feeling like I went to war and lost. For those of you wondering, yes you can use a V frame engine hoist to lift your machine onto the mill stand and no it's not easy to get off the pallet as the frames legs are not nearly wide enough. I ended up strapping the head to the hoist and used the 1 ton setting on a 2 ton hoist(but first I strapped the head down so stress didn't end up on Z axis ballscrew/gibs). I then hoisted the mill up a little while dragging it sideways until it was on the corner of the pallet and pretty much dead center under the hoist.

Now I'm taking on the task of familiarizing myself with the mill and Mach 3 and have everything moving at this point but cannot seem to get less than .002" of runout at the shank of my end mills(tried two so far). I'm using a Tormach R8 3/4" collet and of course Tormach ER20 tool holders. I have ensured inside the spindle and outside of the collet is clean and I have tried several methods for tightening the drawbar down which is a long bolt with a nut style. At first I tried tightening the bolt until the R8 collet was all the way tight on the tool holder ignoring the nut and then I tried screwing the bolt/drawbar down to point where about 1" of threads remained and then tightening just the nut down. I am also ensuring that the tool holder is completely pushed into the collet while tightening the drawbar.

Now I'm wondering if it has something to do with the tension at which I tighten the drawbar or maybe the spindle needs to be rebuilt. Honestly I expected closer to .0005" of runout at worst case but after wiggling the tool holder with some force I'm seeing about .0015 of play which I'm guessing could be the spindle bearings? I tried locking the gibs down real good and did not notice any improvement. Hopefully the fix will be cheap as I'm about tapped out for the moment...


Appreciate any adivce or input!

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[hax0red]

Put some pressure on the head itself and found the slop is actually in the Z axis. Managed to tighten it up to about .001" of slop so far. I also tried a third Tormach ER20 tool holder with new end mill and finally I'm far seeing less than a quarter graduation of movement on my .005" indicator so I'm thinking it's .0005" or less now. Ordered a new Shars test indicator that should deliver roughly .0001" measurements so I will get back later this week with exact numbers on the slop and spindle runout. Some good news is I cannot seem to find any slop in the X or Y axis no matter how much force I apply with the indicator against the end mill.

Here is the DTI I ordered:

SHARS 008" Large 0 4 0 Dial Test Indicator 0001" Case New | eBay

Hopefully it turns out to be a decent piece. I wouldn't mind if it was .0001-.0002" off long as it holds up for a few years. So many tools to buy and so little money

[gd.marsh]

Once bitten by the CNC bug .. it's pretty difficult to shake it off.
You experience so much enjoyment, satisfaction, & sense of accomplishment . . . . . frustration, anger, & expense as you learn how to make your machine do exactly what you want it to.
I doubt that you'll be able to hold 1 or 2 tenths with a Chinese conversion, but if you're doing primarily hobby work plus or minus a few, to several thou is sufficient in most cases.
Unless you already have a fair amount of machining experience you should also consider purchasing cheap end mills to get started .. there's quite a difference in quality between cheap & expensive tooling, but you will likely break or destroy several as you're developing your CNC skills ..
But with all that said .. you've embarked on an incredibly addictive hobby! Best of luck & post pictures of your journey!

gd.marsh

[hax0red]

Once bitten by the CNC bug .. it's pretty difficult to shake it off.
You experience so much enjoyment, satisfaction, & sense of accomplishment . . . . . frustration, anger, & expense as you learn how to make your machine do exactly what you want it to.
I doubt that you'll be able to hold 1 or 2 tenths with a Chinese conversion, but if you're doing primarily hobby work plus or minus a few, to several thou is sufficient in most cases.
Unless you already have a fair amount of machining experience you should also consider purchasing cheap end mills to get started .. there's quite a difference in quality between cheap & expensive tooling, but you will likely break or destroy several as you're developing your CNC skills ..
But with all that said .. you've embarked on an incredibly addictive hobby! Best of luck & post pictures of your journey!

gd.marsh

yeah I'm hoping to hold .001 or so but really the finish quality is what I'm after. I'm hoping with some mods, slow cutting speeds and attention to quality I can get close to a PCNC 1100. I've seen quite a few of these 45 clones get close and I'm not sure the owner had the level of finish in mind that I'm looking to achieve.

That said, I managed my first use of hsmxpress tonight along with my first cuts on some blocks of wood. Everything went extremely well considering a day ago I had no idea how to do anything in a cam program or how to setup a part on the mill. Once I get all of my end mills tested and setup in my cam program I'll move onto some aluminum I have here and have a try at some actual parts I've had in mind for quite awhile.

OK off to bed!

[hax0red]

Got the Shars guage and have been able to get the run out at the end mill down to .0005 on occasion but if I simply loosen and re-tighten the Tormach R8 adapter I usually end up with .0012+ run out. I have attached a photo of the guage indicating. With no collet just measuring off of the R8 collet I get pretty much zero movement(less than a quarter of .0001" at the top, middle and bottom of the R8 taper inside the spindle.

Measuring at the tool things are super inconsistent and I'm just not sure why. Would going to a powered draw bar help or should I consider moving to BT30 + powered draw bar tooling like some have done?


Update: tried running just a grizzly branded 1/4" R8 collet that was included with mill and a broken 1/4" end mill. Ended up showing the exact same run out I saw from the spindles R8 taper which is pretty much 0.000025 or less at the end mill(second picture). Also tried a second using the grizzly 5/16" R8 collet and a $4 end mill which resulted in around .00015" of run out.

[skipmarcel]

Hax,

Are you still using your PM-45?

I have found a used one and wondering if I should buy?

Thanks for any input!

[pastaman]

Hax,

Are you still using your PM-45?

I have found a used one and wondering if I should buy?

Thanks for any input!

I saw your post above asking about a PM-45 CNC mill. I have a PM-932 CNC mill loaded with extras. If interested I will PM you the data. BTW - I'm in the Reno, NV area.

[skipmarcel]

I saw your post above asking about a PM-45 CNC mill. I have a PM-932 CNC mill loaded with extras. If interested I will PM you the data. BTW - I'm in the Reno, NV area.

I’d like to see it for sure. I don’t know that PMs are working in this site right now, but you can email me:

Tyler@grizzlytattoo.com