PM-25MV and clones, all the same for CNC conversion?

[graham-xrf]

Hobby Machine sized small mills that we have space for, and can reasonably save up for, and has some potential for some upgrades like CNC. I really wanted to go the route of those folk who have successfully fitted CNC conversions. We know all this kit comes from China. Several brands, but let us not say "alike", because they are more than that! . One gets small variations, but alike enough to say "more than clones". What I see is stuff so alike, it does kinda look like the Cosmoline was probably applied to all of them by the same urchin in China! Right down to the symbols on the plastic push-buttons!

In UK, options for buying Precision Mattews were always limited. There are real problems if wanting to import. At the time I ordered, UK was in the last stages of being in the EU, though that arrangement was shortly to crash out! I opted to go with the Cormak from Poland, though only a day or two into encountering the Brexit mess!. Cormak do precision CNC stuff in Europe.

OK, I admit I may have overdone this to the point of boredom, for which I apologize. I could have used a one-liner like "In that size, they all come from China and are pretty much similar", but this whole scene has got my hopes up. They are not just "similar". They have so much common DNA that I think it probable that the main metal chunks all saw the same cutters in the same manufacturing facility. It is possible that some, say made with Precision Matthews, or Cormak logos, might have been finished to a better specification, (for more money). There are some variations in the motors. Some are described as 750W, others as 1kW, some as 1HP. Some might have a inches tape riveted on. There might be plastic gears in there.

Notice the common giveaway. The type number will be some combination with a "25" in it, and if there is a "V" or a "M" or both in any combination, and when they look alike, it kind of makes it a certainty! In the important features, these are maybe more than just "clones". They might be simply the very same steel, smelling of the very same oil from the very same drum!

Hopes for CNC Conversion Kits Compatibility?
The whole reason I have hopes is that I now think it possible all those CNC conversion project videos for PM-25, Grizzly, and others, the plans, the various ballscrew + bearings and motors conversion kits from vendors, might, down at the place they get bolted on, be nicely compatible. Sadly, unless there is a UK outlet for the kits, or they can be found on eBay, I might still be looking at an import headache, or I make the machine manufacture it's own conversion kit to my own preference.

There are slight differences, but here's why I think these all came from the same square mile..

Cormak HK-25L (Metric from Poland). I opted for the one with the X-drive motor. It's Polish, from an outfit with a good rep.

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Looking familiar? So how about Precision Matthews PM-25MV
You can get it with optional stand, X-motor drive, Imperial units, other voltage options, etc.



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Yes, we know that when we consider Grizzly G0704, it is also described as a "PM clone", though I am not sure which was there first. I have even seen a video doing a "compare" between them. The Grizzly was about $1350, compared to PM about $1600 to $1700. Maybe PM paid for a better build? This type is known to feature at least one plastic gear, which folk simply change out.



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From Germany, we can have Weiss-VM25. This one is so exactly like the Cormak, I think the only difference is one label!
The one shown is without the motorized X-drive option.


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Now that I am onto this game of "spot how identical we are", I may as well keep going, though I dare say those I find might not comprise even a minority list!
One can find the Titan TM25V. That one even has the identical start/stop switches and electrical panel layout as PM-25MV, and is, I think 110 Volts type



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We can discover the RCOG-25V. Same as, same as..


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OK Graham- that's enough already!

 

[markba633csi]

There are differences in the drive systems, for example, the Grizzly G0704 has plastic gears that break whereas the PM-25 has belt drive
The motors are different too
-M

 

[graham-xrf]

I knew there would be different builds. I had heard that Grizzly folk do gear upgrades. The idea of plastic gears seems somehow "wrong" in the context of mills, but I also know that one can get high performance plastic and composite gears that are quiet, don't wear much, and are used in modern industry. I know I have a bit of a bias to steel, but, feel free to let us know your opinion of plastic gears in mills.

What I was hoping for was that the internals where the lead-screws are, the main slides measurements, clearances, etc. would be the same to the extent an available CNC ball-screw + motors kit would just fit on OK without too much hassle.

 

[markba633csi]

In theory plastic gears should perform well but in practice the factory often cuts corners (weak material, insufficient mass and surface area)
leading to early failure

 

[graham-xrf]

While we are spotting differences, the base of the PM-25MV, and similar looking Titan TM-25V looks to be made specially lower, more saving of Z-axis height clearance, which seems to be about an inch extra compared to Grizzly, Weiss, and Cormak. These three seem to have the same basic shape base. Taking a guess, does the "M" in PM-25MV mean "manual"?

Another place differences will be seen is in the spindle fitting. PM-25MV has a R8 collet chuck with drawbar. My Cormak has a MT3 with drawbar. They supplied M10 thread drawbar , but all my tools use M12. This is easy enough changed.

I am not likely to simply trust that they "look enough the same" to commit to purchase of a CNC conversion kit. Either I manage to verify the fit in some way, or I have to take mine apart, and measure. Otherwise, I find info about someone who has done it before. The Weiss and Cormack look so near identical, that I think there may be a reasonable chance the Paul Schaffner YT series on CNC conversion may work OK.

 

[Oldseabee]

In the USA right now the Weiss pm25 seems the best deal. Free shipping from Tool Lots . Grizzly want 289 to ship go704
I'm calling them tomorrow. Maybe they know of a conversion kit. Over fit and finish sure looks to be of a higher quality then LMS model or Grizzly models. And right now they are on sale

 

[graham-xrf]

In the USA right now the Weiss pm25 seems the best deal. Free shipping from Tool Lots . Grizzly want 289 to ship go704
I'm calling them tomorrow. Maybe they know of a conversion kit. Over fit and finish sure looks to be of a higher quality then LMS model or Grizzly models. And right now they are on sale

Hi there.
Since we are on the same path, maybe I can let you know where I have already been trawling, and what I have found.

In all the conversions, they all have to deal with getting a ball-screw kit to fit in the gap without bumping into limited spaces under the table, and how to get the motors mounted. Let's go a little slower for a bit, and take a look back at the images of the look alike mills.
Concentrate on the shape of the base, and note there are only two styles.

See the Grizzly G0704, and the Weiss-VM25, and indeed my Cormak HK-25L are all the same. This means that your choice is right where you will find all the kits and help video you could want. You mention Weiss pm25, which is not exactly the same code as I know, and "pm" is normally associated with Precision Matthews.

There are some small differences in the build, the Precision Matthews one using a single table casting which includes the end plades, whereas the G0704 style has separate steel plates bolted on at each end of the table. The different base on PM25 is flatter and lower, which gives the Z-axis a little more length. There are some other differences, and also the Taiwan build is different enough to the generic Chinese to account for the higher price of PM kit.

One of the difficulties is getting snookered "Catch-22" style in having the mill all taken apart when you need it to machine bits for itself. This is what drives the sale of kits with all the end bits and motor mounts already made. It helps if you have a CAD model of exactly the machine in front of you, so you can go exploring in it.



The files are in STEP format, rename to .stp if you like. STEP is the universal protable format understood by all CAD software. Various proprietary softwares will import them, but insist on exporting in their own format. I use FreeCAD, which is just promiscuous when it comes to file formats.

The text file with video links
I attach the text file here. It is my collection, and there is no civilized way to simply post the links here. In it you will find the links to video instructions for Weiss VM25L, G0704, PM25-MV
Note that small variations in the codes usually describe options. In my case, the "HK25-L" means the variable speed drive spindle, and the X-axis motorized travel.

Look in particular at one which describes a small mod cut-out to tha casting to clear the ball-screw, and give back more than what would be lost in Y-axis travel.

The available kits are mentioned, and linked to in the video descriptions, but you can just Google them. If there happens to be a lot of stuff you already know, then I apologise, but lets have that other HM members might want the whole 9 yards of getting to know about how to do this, and what is the best stuff, and what to avoid, and mistakes not to make.

Just to put some examples here, as included in the text file, try these...

Grizzly G0704 CNC Conversion with Closed Loop Steppers - the start of a series

Paul Schaffner's CNC project Weiss VN25L, which looks much like a Cormak, and a G0704
Here is part 1

 

[Oldseabee]

Thanks, you have saved me time and probably money too.

 

[graham-xrf]

Further to the discussion with @Oldseabee about CNC conversions (and kits) for Weiss, G0704, etc, and the similar Precision Matthews PM-25V (and similar PM25s)
This stuff is for those who have the Precision Matthews PM-25 in mind. I include here a quite detailed CAD model information, with pdf drawings, and iges model format. The picture is from my FreeCAD, where I was measuring it's parts. You have to zoom up some to get what I was up to. It is a public domain model, so use it to figure out how to carve on your PM25, and make up plates to mount motors, etc.



As mentioned, the set of PM-25 drawings, and models in iges format, which is also an industry standard understood my most CAD software.
Here is an example..


The whole lot are in the ZIP file
I have all that hung together in a FreeCAD model, but I have not (yet) selected all, and exported in STEP model format. The file just too large (22MB) to post here. I think that is because it is so highly detailed.

Most folk should be OK with loading up the iges models included here. If anyone wants it, I can put the FreeCAD model on my server and leave the link here. Alternatively, @vtcnc, I know, has ways of making big file stuff available to members.

For now, my CNC ambitions have to go behind the stuff I still have to do to my house, and my xrf project.

 

[Oldseabee]

I'm interested in the cad file. I have not used cad in years. I guess it time again. Maybe this old dog can learn new tricks.