# Pm727 Questions



## sfsteel (Feb 16, 2018)

Hi everybody,

Hobby-Machinist.com rookie here 

I’m looking into purchasing the PM-727, and I see a lot of members here own this machine. I have a few questions.

1). PM-727v versus PM-727m... is the variable speed worth the extra money? I havent seen any complaints about lack RPM control on the standard 727m model. Am I overlooking something that is highly beneficial about the variable speed model?

2). My research shows that it’s popular to mod geared machines over to belts (particularly with the G0704). Never the other way around. The 727 has a six speed gearbox, which I do not want to modify. How are the gear boxes on these machines? Does anybody have any gripes with noise or gear switching?

Thanks in advance!

Patrick


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## mksj (Feb 16, 2018)

Hi Patrick,

My last bench top mill had a 3Hp BLDC variable speed motor with a 3 speed gearbox to cover a speed range of 50-3000RPM. Variable speed allows you to change speed on the fly and dial in a specific speed for the work conditions. It makes it much easier to get the optimal speed and feed. Trying to achieve this with just a 6 speed gearbox w/o variable speed is cumbersome and the speed steps are very large. Given the choice and nominal cost difference, variable speed is the way to go. You need the six speed gearbox to give you the power band for each variable speed range which I would estimate would be 40-100%. As you decrease the variable speed down you loose Hp.

The main reason for a belt conversion is noise (which I have not heard as an issue with the 727V) and increase spindle speed. You are getting a mill with a 1 Hp motor, so you need the gearing steps or multiple pulley steps to provide the mechanical ratio within the operating range of the variable speed motor. Most people that convert to belt drive use two steps and use a larger motor, otherwise the performance will suffer. Conversion to a belt drive is usually done on conversion to a CNC machine where you they are spinning the spindle at much higher speeds using a small bit. Converting a PM-727V to a belt drive would compromise the machine significantly if using it only for manual milling. You would also be spending a lot more money unnecessarily converting a PM-727V to belt drive vs.  buying a PM-30MV which comes with a 2 speed belt drive with a 2Hp motor.

Both the PM-727V and PM-30MV, offer an optimal milling package in my opinion for their size and price.  If you need a smaller footprint and/or only have 120V go with the PM-727V, if you want belt drive and have 220V go with the PM-30MV. Size matters, but as far as travel (X, Y, Z) the 30MV gives a bit more X travel, but otherwise they are very similar in this category. If you have 220V, the PM-30MV would be my recommendation. Be aware that the cost of equipping your mill (vise, chucks, end mills, etc.) can easily be the same cost as the mill itself.
Mark


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## wrmiller (Feb 16, 2018)

Many folks converted the G0704 to belt drive to eliminate the plastic gears in the drive train. I did the same to a early PM25 for the same reason. Having said that:

I much prefer variable speed machines, primarily for the reasons Mark explains above. The ability to 'dial in' the rpm can improve surface finish and prolong tool life.

I have a preference for BLDC motors over A/C motors. Better efficiency and power across the rpm range. A/C motors have a narrower power band so require gearing to provide a broader spindle rpm range while keeping the motor in or near it's optimum power/torque range. A BLDC motor is basically a 3-phase motor that is driven/stepped by DC electronics (similar to a A/C powered VFD and 3-phase motor combination).


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## T Bredehoft (Feb 16, 2018)

With a variable speed you can fine tune the "harmonics" of an end mill. Sometimes changing the speed by 10% will smooth out a cut.


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## tweinke (Feb 16, 2018)

I have been very satisfied with my 727m. I agree with Bill and Tom above about the variable speed and think if it were in my budget i would go that way. The v model was not available when i bought mine. I'm two years in as far as ownership and the gearbox has been no issue, the one issue i did have with the motor was taken care of by Matt quicker and easier then i ever would have imagined. Another words Very Satisfied.


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## sfsteel (Feb 16, 2018)

The website does not specify the motor type. So I'm assuming it's A/C? 

BTW, I'm not planning to convert to CNC.

I would love to get the PM-30MV, however I don't have 220 in my shop. I may need to investigate running a new line of power out there though. For an extra $50 I get more girth, bigger table, significant X axis travel, and a brushless/belt setup. 

I started out thinking I was going to purchase the G0704 -> Pm25mv -> PM-727m -> PM-727v -> and now the PM-30MV.

Funny how that happens...


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## wrmiller (Feb 16, 2018)

sfsteel said:


> I started out thinking I was going to purchase the G0704 -> Pm25mv -> PM-727m -> PM-727v -> and now the PM-30MV.
> 
> Funny how that happens...



Ha! I started with a Sherline, then a cheap chinese table-top, then a LMS, then a early PM25, then a 9x40 Charter Oak, and then on to my current 935TS. There won't be any more...


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## ttabbal (Feb 16, 2018)

Sounds like my lathe decision tree.. HF mini-lathe > grizzly 10x > PM1022 > PM1030 > PM1127. I also considered trying for the PM1236, but I think the wife would have used it to make decorations from my bones after killing me.


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## sfsteel (Feb 16, 2018)

It looks like my buddy, who is a commercial electrician, is going to help me route a dedicated 240 line to my shop, so the 30mv is looking more and more attractive


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## wrmiller (Feb 16, 2018)

sfsteel said:


> It looks like my buddy, who is a commercial electrician, is going to help me route a dedicated 240 line to my shop, so the 30mv is looking more and more attractive



When I bought my PM25, I REALLY wanted the PM30, but Matt discontinued selling the Weiss-based PM30 (and PM25) because of quality issues. Years later he comes out with a new and improved PM25 and PM30, but I had already moved on to a larger machine.

My timing over the years has never been that great. If I had just sat on my hands for about 6 years or so, I could now have a PM949TV and a PM1440GT sitting in my garage. But how was I supposed to know? Oh well, coulda, woulda, shoulda...


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## 19E60 (Feb 17, 2018)

+1 on the PM-30MV, I have one as my first mill and am very pleased. It has done everything I've asked of it. Definitely recommend it for the variable speed, belt drive, and more hp over the 727. When we move in a couple years I will upgrade to a knee mill but keep the 30, thinking of diving down the cnc rabbit hole on that one.


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## SSage (Feb 18, 2018)

Pm727m, hardened gears, no belts to change, simple manual gear box. The variable speed version gives you much more rpm.

I went with the manual, I just don't "need" any more electronics to possibly repair. I don't run at 1700 rpm often, I don't need the higher rpm working in my usual steels. I have a manual 1236 too, it's just preference and cost.

I really like the manual gear box, no changing belt position for the hi/lo ranges. It's a nice option over the PM25. I run slow often drilling 1" holes, the quick gear changes are nice compared to my belt drive machine. The 727 runs good at low rpm and doesn't struggle at all. Well, at least with a 1" drill bit in 1018. 

I have been thankful I did get the pre-installed DRO. My first, should of bought a mill with a dro years and years ago. I'll probably add dro to my 1236 too.


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## wrmiller (Feb 18, 2018)

SSage said:


> Pm727m, hardened gears, no belts to change, simple manual gear box. The variable speed version gives you much more rpm.
> 
> I went with the manual, I just don't "need" any more electronics to possibly repair. I don't run at 1700 rpm often, I don't need the higher rpm working in my usual steels. I have a manual 1236 too, it's just preference and cost.
> 
> ...



This is a good example of buying a machine to fit it's intended purpose. SSage drills large holes in steel. Not everyone does. I do have a 1" drill bit, somewhere, but have never used it. Someday I might. 

If you are leaning towards doing lots of heavy(er) work in steel, a gear head makes sense. If you are doing smaller projects in aluminum, you would benefit from a higher spindle rpm.


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## sfsteel (Feb 18, 2018)

wrmiller said:


> This is a good example of buying a machine to fit it's intended purpose. SSage drills large holes in steel. Not everyone does. I do have a 1" drill bit, somewhere, but have never used it. Someday I might.
> 
> If you are leaning towards doing lots of heavy(er) work in steel, a gear head makes sense. If you are doing smaller projects in aluminum, you would benefit from a higher spindle rpm.



Interesting input (also from Ssage ), I like working with steel, particularly because I can weld it easily with my MIG machine. I almost never work with aluminum (as of now). The 30mv still seems attractive to me, unless somebody convinces me it’s not a good machine for steel. I like the extended X travel, larger table, and smooth belts.

As an audible, I’m also tossing around the idea of forfeiting the variable speed/belt and step up to the 932m-basic. It seems like double the machine as far as weight/rigidity is concerned. I wasn’t considering this before as I didn’t have 240v lined up.

Matts’s Product lineup really makes these decisions hard.


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## wrmiller (Feb 18, 2018)

The PM30 is more than capable of working with steel. My PM25 worked with steel. But, these smaller machines are not ideal for heavy machining in steel. Too much flex.

Drilling is one thing. Milling is quite another. 

If you are intending to feed your machine a steady diet of 1/2" thick and larger chunks of steel, and drilling huge holes it it, then you might be looking at too small of a machine. These machines can do it, but you won't be running a 5/8" end mill buried to the hilt in a 1" steel plate on either of these machines. The 932 would be a much better choice IMO.

The only machine I owned (prior to my current one) that could bury a 5/8" end mill in steel was my 9x40.


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## SSage (Feb 19, 2018)

The pm727m was purchased to replace an antique huge 3ph Bridgeport manual machine. I'm only working on small tools and dies.

I wondered if a small bench mill could machine out my 1" thick die blocks and it's really been no problem. The motor only gets warm after a couple hours of drilling, milling slots and squaring up the faces etc. I try and run things slow and cool with a mister, the large hss 1" drill bits dull quick when the temp rises and things steam. I haven't had any issue machining down steel bars with little 1/2" end mills. Just use tooling that matches the mill's power. 

I realized I could condense my work shop into one fairly small room. In retrospect, I'm happy with my setup. But I have a narrow set of projects, it helps greatly to buy the machines big enough to satisfy your actual work. I like my home shop small, my hobby is getting more like a real job enough already.


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## Maine (Feb 19, 2018)

To get 220V, you can always use two different breakers. I did it for $20!


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## sfsteel (Feb 19, 2018)

Maine said:


> To get 220V, you can always use two different breakers. I did it for $20!
> 
> View attachment 258784




YIKES!


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## sfsteel (Feb 19, 2018)

On the topic of Aluminum and Steel, I noticed the PM-727 and PM30MV run at max 3000 RPM. 
The PM932 maxes out at 1970 RPM.

If I wanted to cut something like aluminum, can I work with 1970 RPM? 

I'm trying to make sense of some RPM calculators, but I'm seeing different results. I know it will cut, but what do I sacrifice by milling aluminum at such a slow speed?


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## phazertwo (Feb 19, 2018)

Maine said:


> To get 220V, you can always use two different breakers. I did it for $20!
> 
> View attachment 258784



That's not sketchy...  




sfsteel said:


> On the topic of Aluminum and Steel, I noticed the PM-727 and PM30MV run at max 3000 RPM.
> The PM932 maxes out at 1970 RPM.
> 
> If I wanted to cut something like aluminum, can I work with 1970 RPM?
> ...



Yes, just run larger tools to get your SFM up.  I have a friend that just runs 0.5" tooling in his mill that only runs 2000RPM.

Do you have any plans to CNC it in the future?

PZ


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## sfsteel (Feb 19, 2018)

Doing some research, it looks like 1970 RPM is going limit aluminum cuts to 1/2" end mill or larger. 3000 rpm will allow as small as ~5/16".

https://littlemachineshop.com/reference/cuttingspeeds.php


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## wrmiller (Feb 19, 2018)

Those numbers you're looking at are for maximizing operations (cycle times, cutter life, surface finish, etc.), under ideal conditions, on much larger/more rigid machines. None of that has anything to do with hobby machining on much, much smaller machines. 

When you are dealing with hobby level machines you are much better off listening to the machine/cutter/material interface during cutting. Your mill and/or cutter will tell you when they're happy, if you just listen and observe. This is why I don't install power feeds right away on a new mill. I want to turn the handles, and feel/hear what the mill is doing when it's cutting. This gives me a better idea of it's capabilities than flipping a switch and turning around to take a sip of coffee.

Each machine is different. Some are tighter than others, some are looser. Some are more rigid than others. Some have more power than others. Etc, etc..

So I needed to mill slots in a hardened piece of steel, using a 1/8" ball endmill. On a tiny Sherline mill. I had a honest to goodness machinist tell me it couldn't be done on that 'toy'. He was wrong. 

Just a suggestion, but don't overthink this. Get your machine(s), get them set up, and experiment. And have some fun while you're at it.


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## phazertwo (Feb 19, 2018)

Don't forget reading the chips... The chip will tell you an incredible amount.

I agree with wrmiller.  A 5/16" cutter at 3000 RPM is ~245 SFM... I consistently cut 150 SFM or even slower with no issues.

PZ


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## wrmiller (Feb 19, 2018)

phazertwo said:


> Don't forget reading the chips... The chip will tell you an incredible amount.
> 
> I agree with wrmiller.  A 5/16" cutter at 3000 RPM is ~245 SFM... I consistently cut 150 SFM or even slower with no issues.
> 
> PZ



Yea, forgot that part. Hey, I'm not perfect.


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## sfsteel (Feb 20, 2018)

wrmiller said:


> Just a suggestion, but don't overthink this. Get your machine(s), get them set up, and experiment. And have some fun while you're at it.


I see the truth in that!

I just placed an order for the PM-30MV. I guess now I wait 5-6 weeks. I was on the fence between the PM932 and the PM30MV, but it appears the 932 is out of stock for at least 6 months. So, easy decision. 

To do:
1. Install 240v
2. Build a stand
3. Buy some tooling 

BTW thank you everybody who provided input on my questions, that was very helpful.


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## wrmiller (Feb 20, 2018)

Outstanding! 

The wait is the hardest part, but it helps if you have things to occupy your time as you do. Now of course we require a writeup with your impressions of the machine, and sprinkled with lots of pics.


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## JohnnyTK (Feb 21, 2018)

After watching a few videos on the PM727 about raising the "Z" axis can be a chore, I was wondering if it is easier to lift and lower on the PM-30 because it has a air spring assist? I have not been able to find any videos or information on this. The PM727 has a bunch of video's on modifying the to a power lift but could not find any on modifying the PM-30. Not an issue of my Sherline.


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## sfsteel (Feb 21, 2018)

I saw those same videos, wasn’t really looking forward to that. I had no idea the Pm30mv had a spring assisted head, until you mentioned it (I confirmed it in the manual). Hopefully a PM30 user can chime in on that, otherwise I’ll let you know when it arrives


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## JohnnyTK (Feb 21, 2018)

sfsteel said:


> I saw those same videos, wasn’t really looking forward to that. I had no idea the Pm30mv had a spring assisted head, until you mentioned it (I confirmed it in the manual). Hopefully a PM30 user can chime in on that, otherwise I’ll let you know when it arrives


OK is it 6 weeks yet?


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## tweinke (Feb 21, 2018)

JohnnyTK said:


> OK is it 6 weeks yet?




Sounds like a car trip with the kids.......Are we there yet?  I'm pretty sure this will be the longest six weeks ever but to make you feel better,  Just a few more days!


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## SSage (Feb 23, 2018)

I waited months on my pm1236, when I got a mill I chose one in stock. Got the mill in a week! Almost felt too fast, I was scrambling to get a spot cleaned out in time.


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## Maine (Feb 23, 2018)

When I purchased my PM-30MV a few weeks ago, there were only "2" in stock, including the one I reserved with a downpayment, before I paid the full amount.


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## JohnnyTK (Feb 23, 2018)

Maine said:


> When I purchased my PM-30MV a few weeks ago, there were only "2" in stock, including the one I reserved with a downpayment, before I paid the full amount.



What is it like to lift the "Z" axis, because many people with the 727 have indicated that it can be hard on people with shoulder or arm problems?


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## Maine (Feb 23, 2018)

JohnnyTK said:


> What is it like to lift the "Z" axis, because many people with the 727 have indicated that it can be hard on people with shoulder or arm problems?



Actually kind of depends on what angle you're moving the handle, but it's not as bad as I thought it was going to be and I'm by no means a "fit" person.


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## Ozbusa67 (Nov 14, 2019)

mksj said:


> Hi Patrick,
> 
> My last bench top mill had a 3Hp BLDC variable speed motor with a 3 speed gearbox to cover a speed range of 50-3000RPM. Variable speed allows you to change speed on the fly and dial in a specific speed for the work conditions. It makes it much easier to get the optimal speed and feed. Trying to achieve this with just a 6 speed gearbox w/o variable speed is cumbersome and the speed steps are very large. Given the choice and nominal cost difference, variable speed is the way to go. You need the six speed gearbox to give you the power band for each variable speed range which I would estimate would be 40-100%. As you decrease the variable speed down you loose Hp.
> 
> ...


I just   Purchase one


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## Ozbusa67 (Nov 14, 2019)

I just pick one up and I love it my fan is loader then the 727v I would buy again and the people there are great I'm going to buy a new lathe soon 1030v. Get it with dro's theirs install is fantastic


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## Ozbusa67 (Nov 14, 2019)

JohnnyTK said:


> What is it like to lift the "Z" axis, because many people with the 727 have indicated that it can be hard on people with shoulder or arm problems?


I just put a motor in mine for about 100.00  it works great


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## Driveslayer45 (Nov 15, 2019)

I have the 727v, love the variable speed. as said earlier you can tune the speed to the cut on the fly.

as for the z lift its not hard at all. due to how close i am to the wall i hold the handle with my thumb and two fingers. kind of pinching it because i cannot get a full grip on the handle, when i raise or lower, no issues.


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