Looking for my perfect size hobby mill....

[wrmiller]

Hi, I own a PM932, I've owned it for about 5 years and worked on it since new, all kinds of problems. it has a single-phase motor that has eaten start caps, severe oil leaks and little stuff.
If I were to do it again, I would purchase a unit with at least a 3-phase motor a DRO and a X axis power feed.
I have in the past purchased Grizzly stuff and was impressed with the amount of tooling that came with them,
I like the G0695 - 8" x 30" 1-1/2 HP Variable-Speed Knee Mill. the PM 728 looks nice.
Rich

As someone else on here said, I like a VFD driven 3-phase on a medium to large machine, or a BLDC on a smaller mill like my PM25. And belt drive so no oil in the head to worry about.

 

[Larry$]

Will the weight of a lathe which is Approximately 1100 lbs. plus the weight of a Mill that's just 6' apart on the same wall pose any issues - I've narrowed down my choice of Mill to either the Pm-727v 575 lbs. or the PM-932 1100 lbs. So that is 1700 lbs. or 2200 lbs. near the footing on the same wall..?

There are so many variable in residential concrete work that a precise answer can't be made. But if the work was done to normal commercial specifications I don't think your proposed loading is an issue.
Variables that affect slab performance: site preparation: Was the compaction of the supporting earthwork uniform? Was any reinforcing used and most importantly was it placed so it stayed near the centerline of the slab? BTW 6,6-10,10 welded wire mesh is typically of little value in my opinion! Was the slab actually at least 4" thick? Were proper consolidation methods use while the slab was poured? Did the mix meet Portland Cement Association standards? Were control joints used? And very importantly was the slab properly cured? If you answered yes to all of these you are in luck! But the slab may still crack!

Given your options, if it was me, I wouldn't worry about it and just put the machines in place. They aren't all that heavy. If they are placed over a control joint or crack you may want to check their leveling periodically to see if slab movement has affected them.

For what it's worth: I managed excavating and concrete work for quite a few years in residential, commercial and Federal flood control dam work. I then got a degree in architecture and aced the structural classes. I've also seen a lot of $hitty concrete work done.

 

[verbotenwhisky]

Couple questions I need help with Please....?

The garage floor where the Mill will live is a 4" thick monolithic slab on grade floor, with 16" deep perimeter footings poured at the same time...The additional weight of these two machines is something I should consider since they are right up against or near the footing that separates the garage and living space.

My question is..?
Will the weight of a lathe which is Approximately 1100 lbs. plus the weight of a Mill that's just 6' apart on the same wall pose any issues - I've narrowed down my choice of Mill to either the Pm-727v 575 lbs. or the PM-932 1100 lbs. So that is 1700 lbs. or 2200 lbs. near the footing on the same wall..?

My second question is..?
Both Mills above share a lot of the same attributes, but the PM-932 has a 9" table that is 2" deeper than the PM-727v... Is the extra size of the 9" a pretty big deal over the 7" ?

Thanks Mike...

2" of additional table in either direction is a big deal but in the Y Axis absolutely. A good vise goes a long way but, eventually you'll want to strap clamp something to the table and the additional width really works in your favor at that point.

The slab should be fine, if there is a worry place small beams under it running the length of the machine to distribute the load over the entire foot print as opposed to the 4 or 6 feet which represent a point load that it normally sits on.

 

[JustBen]

Couple questions I need help with Please....?

The garage floor where the Mill will live is a 4" thick monolithic slab on grade floor, with 16" deep perimeter footings poured at the same time...The additional weight of these two machines is something I should consider since they are right up against or near the footing that separates the garage and living space.

My question is..?
Will the weight of a lathe which is Approximately 1100 lbs. plus the weight of a Mill that's just 6' apart on the same wall pose any issues - I've narrowed down my choice of Mill to either the Pm-727v 575 lbs. or the PM-932 1100 lbs. So that is 1700 lbs. or 2200 lbs. near the footing on the same wall..?

My second question is..?
Both Mills above share a lot of the same attributes, but the PM-932 has a 9" table that is 2" deeper than the PM-727v... Is the extra size of the 9" a pretty big deal over the 7" ?

Thanks Mike...

If it helps. I had a two post lift installed on a 4" thick (Measured by contractor) concrete pad. The bay design made it so the left post had to go within a foot of the edge of the slab against a block wall. Not ideal. After lifting some cars and trucks up to ~4100lbs the concrete developed cracks at the anchors (outside of post with the most leverage applied) as they were pulling up. These cracks were for the post away from the wall.

Long story short, the pad was not 4" everywhere and was likely 3.25" on average. The compression strength of the concrete was good to go at the pivot point of the post and didn't mind the weight, but the force of the wedge anchors being pulled cracked the slab. If that makes sense.

Sounds like you have a good known thickness slab. I would imagine the weight of the lathe being fine. Anyone parking their supercrew truck next to the wall in a garage is putting some good weight on each tire separated by ~11 feet or so.

 

[Larry$]

the force of the wedge anchors being pulled cracked the slab.

Wedge anchors exert huge pressures on a slab. Made worse by using them in relatively thin slabs, 4" where they go nearly all the way thru the slab thickness. There is no need to anchor a lathe or mill to the slab. It might result in stresses in the equipment. It is common practice to use 2x4s or 2x6s to form a slab and not have the slab be any thicker than that 3.5 or 5.5" and be called 4 or 6". Other ways contractors with low standards save $ on concrete work: Specify less cement in the mix (3500# rather than 4000# @ 28 day strength) Put additional air entraining agent in. Add water to make it easier to pour (less labor) Specify the cheaper aggregate choice. (Around here 47B limestone costs more than sand/gravel) Not curing properly is one of the most common ways to reduce cost and strength.
Know what you are buying!

 

[Mr Mike]

Hi, I own a PM932, I've owned it for about 5 years and worked on it since new, all kinds of problems. it has a single-phase motor that has eaten start caps, severe oil leaks and little stuff.
If I were to do it again, I would purchase a unit with at least a 3-phase motor a DRO and a X axis power feed.
I have in the past purchased Grizzly stuff and was impressed with the amount of tooling that came with them,
I like the G0695 - 8" x 30" 1-1/2 HP Variable-Speed Knee Mill. the PM 728 looks nice.
Rich

Hello...
I appreciate the info on the PM-932, I hate oil leaks. With all my research I found that the PM-728 is mostly a better quality version of the Grizzly G0704 that I am currently doing a tear down & clean up on.... The G0695 you point out looks like a very capable machine with plenty of range.

If you don't mind me asking, if you worked out the bugs in your PM-932, would you say its a pretty decent capable machine for a first hobby Mill.

 

[Mr Mike]

There are so many variable in residential concrete work that a precise answer can't be made. But if the work was done to normal commercial specifications I don't think your proposed loading is an issue.
Variables that affect slab performance: site preparation: Was the compaction of the supporting earthwork uniform? Was any reinforcing used and most importantly was it placed so it stayed near the centerline of the slab? BTW 6,6-10,10 welded wire mesh is typically of little value in my opinion! Was the slab actually at least 4" thick? Were proper consolidation methods use while the slab was poured? Did the mix meet Portland Cement Association standards? Were control joints used? And very importantly was the slab properly cured? If you answered yes to all of these you are in luck! But the slab may still crack!

Given your options, if it was me, I wouldn't worry about it and just put the machines in place. They aren't all that heavy. If they are placed over a control joint or crack you may want to check their leveling periodically to see if slab movement has affected them.

For what it's worth: I managed excavating and concrete work for quite a few years in residential, commercial and Federal flood control dam work. I then got a degree in architecture and aced the structural classes. I've also seen a lot of $hitty concrete work done.

Hello Sir..
Its a track home, I'm guessing fast and dirty just passing minimum standards. the property has a good swale around it so no water ponds around the footings, a golf ball test where the machines will sit appears to be in full contact with the soil, the rest is anyone's guess..

I'm less concerned about the lathe because the weight is somewhat distributed but the mills weight is more concentrated... Probably over thinking it as usual.

Thanks for the info, Mike.

 

[Mr Mike]

Sounds like you have a good known thickness slab. I would imagine the weight of the lathe being fine. Anyone parking their supercrew truck next to the wall in a garage is putting some good weight on each tire separated by ~11 feet or so.

Hi..
I think your right, I'm just being a worry wart...

Thanks for the reply, Mike.

 

[Mr Mike]

Hey Mike,

I don't know what a standard garage slab is, spec-wise, but I had a PM935 and a PM1340GT about 6' or so apart along the back wall of the garage and nothing broke.

Hello..
I should have thought it through a bit more, I just tend to worry about the unknown... Thanks.

 

[Mr Mike]

2" of additional table in either direction is a big deal but in the Y Axis absolutely. A good vise goes a long way but, eventually you'll want to strap clamp something to the table and the additional width really works in your favor at that point.

The slab should be fine, if there is a worry place small beams under it running the length of the machine to distribute the load over the entire foot print as opposed to the 4 or 6 feet which represent a point load that it normally sits on.

Hello Sir.
Rich Burg said a few posts back that he's had a lot of issues with his PM-932, real bad oil leaks and such... wonder if that's an issue with other gearhead mills as well, If I remember you have the Variable speed version so you wont have that issue, Have you heard of anyone else with gearhead mills that have excessive oil leaks..?

Thanks Mike.