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Brand new mill table hardness dilemma.

DTM0

Plastic
Joined
Aug 10, 2018
Does anyone know if there is a standard typical hardness, or any information for milling machine tables?

Long story short. We have recently purchased a new Fortworth csvbm-5vl, and the table is incredibly soft. Our other mill tables test out at about 55-60 rockwell C, but this fortworth shows 20 rockwell C. This is makes it very difficult to not damage as even a single chip caught under a parallel, or a toe clamp bolted directly to the table will cause a large dent.

I cant recall any of the shops i have been to needing to put parallels under a toe clamp in order to not damage the table.

The supplier claims that this is actually a feature for superior vibration dampening, and to not mark up the parts youre machining. (hardened parallels and vise jaws seem to go against the "marking up parts" theory.. no?...)

They follow this up with saying these benefits outweigh the con of having to resurface the table with a stone every so often. I strongly disagree.

Anyways, has anyone else experienced this? have any suggestions? Is there any companies that create custom meehanite tables?
 
Interesting
I personally work around old school manual machines ive never heard of or seen a machine tool with a HARD work surface only hard ways

Chips under anything are a big no no in every shop I've worked at but whatever
What machine do you have that has a hard work surface
Got a pic or two ?
 
55-60RC is near bearing ball hardness, much harder than I'm used to seeing in my machine tables. But cleanliness should be a given when setting materials or vises down, surely you'll ding a vise base if clamping on a chip rather than cleaning properly first.

I'd look at your procedures and standards for cleaning before I'd get so concerned about table hardness.
 
i understand chips are to be cleaned. i was using it as an example of how easy this table is to damage, not that we clamp chips into our setups.

either way, simply tightening 2" wide toe clamp down, will cause a 2" wide dent.

the other machines in question with the hard tables are TOS FGS's

our Kent also has a significantly harder table
 
Well, the toe clamping does sound too soft, my Haas's aren't great machines but the tables will take that sort of use. But if it's an edge load I'd still use a Al plate under the clamp edge just as good practice.
 
I haven't a clue (never checked) as to how hard my tables are but I know I can stone or file a riser down with relative ease.
We used to have all the large mills with over size aluminum sub plates permanently bolted down with hardened 1/2" bushings for pins and four 1/2"-13 inserted bolt holes around each pin hole. They used them 24-7 for years on end with only ever removing them if it was required to get to something broken on the machine. I can't see how your cast iron table could be any softer or more easily damaged than those?
Dan
 
Tried to edit my post. Ended up deleting it. Whoops

I guess we have been spoiled with our previous mills. 30 years old and the tables still look brand new.

Yes the machine wasn't too pricey. $100 000 to our door.

How soft the table is just seems very foreign to me. Not what I had expected there. However the rest of the machine is great. No complaints other than the table
 
Wow, that much? Of course in Loonies, but still. I don't usually say this, but did you check out a Haas of roughly the same size? Did you require an open-frame machine for your needs?
 
Tried to edit my post. Ended up deleting it. Whoops

I guess we have been spoiled with our previous mills. 30 years old and the tables still look brand new.

Yes the machine wasn't too pricey. $100 000 to our door.

How soft the table is just seems very foreign to me. Not what I had expected there. However the rest of the machine is great. No complaints other than the table

Mayabe a sub plate would help?
 
Wow, that much? Of course in Loonies, but still. I don't usually say this, but did you check out a Haas of roughly the same size? Did you require an open-frame machine for your needs?

Right there with you , sounds a lot for the machine in YouTube video.
 
Right there with you , sounds a lot for the machine in YouTube video.

Yeah, but the Can buck is about (or aboot) 75% of a US dollar, so that's roughly $75K here (or less). I don't know what the equivalent Haas would go for, but perhaps another $20K or so. And if they need open frame, you'd have to remove the shielding and fudge the safety interlocks, that may be a no-go for their purposes.

But having a tool changer makes so much of a difference in functionality, I wouldn't buy a machine without one unless I absolutely had too.
 
It may seem like a lot. But try getting anything to your door in Canada. You'll find its a pretty good price for what you get.. hell a 8" Kurt vice is 2000 alone. Oil skimmer? Another $600.

Yes it has the pneumatic draw bar.

My only gripe is how soft the table is.

Anyone have hardness testers? I'm curious as to what other people's machines test at.
 
Did you notice the operator was both wearing gloves AND had no eye protection at all?
This was obviously NOT filmed in any American shop. LOL
 
Our other mill tables test out at about 55-60 rockwell C,

I say no way, jose, unless you have very unique mills. I have seen a lot of mills over the years, and every one of them has had a cast gray iron table. I am sure some are harder than others, but none are that hard. How did you take the hardness measurements?
 
I have seen quite a few machines with the T slots all crumbled away underneath by t bolts.....that is probably more of an issue than the surface of the table..which can be easily cleaned up if its a big issue.
 
....... Our other mill tables test out at about 55-60 rockwell C, .....?

How was this tested? I am really suspect of this range of numbers as a bit out there.
This does not make any sense for so many reasons in the world of machine building.... one could hard chrome....

Meehanite which is a trademark and comes in grades is generally in the mid to high 20s Rc so not much of an improvement..
Bob
 








 
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