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Surface Finish Issues on New Machine

Vancbiker

Diamond
Joined
Jan 5, 2014
Location
Vancouver, WA. USA
If the machine is box ways on Z you may have gibs on the keeper plates that need adjusting. Some machines with box ways don’t use gibs and the clearance is set by step grinding the keeper plates.

In any case those steps are up to the builder on a new machine.

If this has linear ways then no adjustment is possible. It’s a design, spec, or assembly error.
 

barbter2

Aluminum
Joined
Nov 25, 2019
Location
On Tour....
"multiple thou"!!!!
Years ago, I did a test on a Bridgeport Boss machine, and with a hand on the head I could get +/-1 thou pushing up and pulling down. That was the swan neck casting flexing.

This is a VMC...you have some serious problem. As Vanc said - could be gibs if box way.
Or you could have loose trucks if rails.
Or loose rails???
 

Rcgiovannani

Plastic
Joined
Apr 6, 2015
A little update.

I put an indicator in the spindle and jogged the machine in the x axis. The indicator barely moved. Very smooth.

I did the same thing on the Y axis and...well, not so good. The needle was jumping all over the place and vibrating like crazy on the initial moves, and then would smooth out after it was in motion for a little while.

This machine has linear roller bearings, btw.

X-axis smooth motion:

https://share.icloud.com/photos/0e50PI4G_phDNPf05l2HnfhoQ

Y-axis jitters:

https://share.icloud.com/photos/00cfgfCqOVcA2NjUgBFidGr0A

running a 2d pocket operation with the indicator zero'ed. Please excuse the poor camera work:

https://share.icloud.com/photos/04aDom604CDqzVmbfaQHdzQCQ

So maybe something loose in the Y axis? I didn't think to try and push on one side of the table to see if I could "skew" the table. I will try that next. Doesn't really explain the z axis head movement I can measure but who knows...

MTB is spending the day with me tomorrow. They're trying, but I need this machine making money!
 

rklopp

Diamond
Joined
Feb 27, 2001
Location
Redwood City, CA USA
A little update.

I put an indicator in the spindle and jogged the machine in the x axis. The indicator barely moved. Very smooth.

I did the same thing on the Y axis and...well, not so good. The needle was jumping all over the place and vibrating like crazy on the initial moves, and then would smooth out after it was in motion for a little while.

This machine has linear roller bearings, btw.

X-axis smooth motion:

https://share.icloud.com/photos/0e50PI4G_phDNPf05l2HnfhoQ

Y-axis jitters:

https://share.icloud.com/photos/00cfgfCqOVcA2NjUgBFidGr0A

running a 2d pocket operation with the indicator zero'ed. Please excuse the poor camera work:

https://share.icloud.com/photos/04aDom604CDqzVmbfaQHdzQCQ

So maybe something loose in the Y axis? I didn't think to try and push on one side of the table to see if I could "skew" the table. I will try that next. Doesn't really explain the z axis head movement I can measure but who knows...

MTB is spending the day with me tomorrow. They're trying, but I need this machine making money!
In the pocketing op it's interesting that the effect from Y motion "sticks" when switching back to X motion. Is it possible the Y way covers have a lot of drag and are pulling and pushing on the column?
 

barbter2

Aluminum
Joined
Nov 25, 2019
Location
On Tour....
Ref the Y....I'm wondering if you have too much backlash in the parameter table?
Which is why the initial jump when direction change?
Or servo tuning issue - when you jog that axis does it whine?
 
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EndlessWaltz

Cast Iron
Joined
Jun 18, 2016
Location
Midwest
I am happy this thread exists and problem solving has been thorough. A great learning device for us here. 1) Don't pay till proven. 2) Drunk guy built on a Monday.
 

Houdini16

Aluminum
Joined
Nov 28, 2017
I hope you get this fixed, I had a similar issue with my brand new Haas DM2, 'basic" servo gain tuning got most of it out, I finally gave up, ball bar shows direction change spikes also, it makes sellable parts, you get what you pay for.
 

barbter2

Aluminum
Joined
Nov 25, 2019
Location
On Tour....
I hope you get this fixed, I had a similar issue with my brand new Haas DM2, 'basic" servo gain tuning got most of it out, I finally gave up, ball bar shows direction change spikes also, it makes sellable parts, you get what you pay for.
Too larger compensation number in the backlash table (per axis)?
 

DouglasJRizzo

Titanium
Joined
Jun 7, 2011
Location
Ramsey, NJ.
It sounds like a paremter
Hello,

I recently purchased a brand new VMC from a company that I would like to keep anonymous for the time being. Let's just say it's a company that has been around for a long time, but they just started selling this type of machine. The important thing is that the machine's weight is about 8600lbs and has X-Y travel of 30 x 20 inches. I was the first shop to take delivery of this machine in the whole country.

I have owned my own shop for about 3 years now and this was the first new machine I purchased. Before this I was using (and still own) a Fryer MB-14. I still work my day job where we have Okuma, Fadal, and Haas machining centers. I have never seen the issue I'm about to describe except for maybe on the Fadal and it's not even half as bad as what happens on my new machine. Not to mention that the Fadal is worth less than 25% of what I paid for the new machine.

The new machine I purchased has a serious issue with "coining" during simple, 2D toolpaths...but honestly it's more like gouging. It occurs when the machine is moving in both X and Y. If I start my feed outside of the material and feed in with a straight line, no coining occurs. If there is a radius on my lead-in then coining occurs at the beginning of the cut. Simple 2D pockets look horrendous.

The machine leaves beautiful finishes when doing 3D surfacing work.

The machine builder has had people out to see the machine from their service team, applications team, and yesterday they had the controller manufacturer come out and take a look. They told me that the problem is the floor in my shop, but I'm not buying it.

The floor in my shop is anywhere from 4-6in thick concrete. They feel that the floor is no good because if you put an indicator on the spindle of the machine and stomp on the floor, the dial jumps around less than 0.0005". Here's the thing though...same thing on my Fryer, but it leaves better surface finishes. Additionally, I put an indicator on a Haas at work and did the same thing and the needle moved more than 0.001"! The Haas leaves perfect finishes.

I feel like the tuning of the machine is just too aggressive and it's "jerking" around when it's changing directions. The machine builder ran a program of mine on one of their showroom machines and it was better, but still not acceptable for the price of the machine.

I'm wondering what you guys think...thanks
It sounds like a parameter tuning or servo tuning issue. Also, is the look ahead active and working?
 

Rcgiovannani

Plastic
Joined
Apr 6, 2015
Hey guys. Sorry for not getting back on here with updates. It's been crazy trying to get parts out through all of this.

I still want to keep the MTB anonymous because they are doing right by me. The machine is leaving the shop and they will be replacing it with another one.
 

thesidetalker

Hot Rolled
Joined
Jan 11, 2015
Location
Bay Area, CA
Hey guys. Sorry for not getting back on here with updates. It's been crazy trying to get parts out through all of this.

I still want to keep the MTB anonymous because they are doing right by me. The machine is leaving the shop and they will be replacing it with another one.
Why not name them?

If you get shit service and support, I think others would appreciate to know who to avoid, or be cautious of.

and if the service is good, wouldn't they also like to know? I'd like to know.

It sounds like they're trying to make things right for you. Why not tell us? Not everybody has stellar service and support these days. I'd rather have a less capable machine as long as it is supported and I can have a technician out in a timely matter should there be a problem. A more capable machine isn't too capable when you have to wait weeks for parts or service, should there be a problem.
 

Houdini16

Aluminum
Joined
Nov 28, 2017
I agree a lot of vendors try not to take the machine back, I want to know who this is so I might buy a machine from a company with this support.
 

Ox

Diamond
Joined
Aug 27, 2002
Location
West Unity, Ohio
I would like to know if Siemens is this companies normal control, or if this was an option?

I'm guessing that this is NOT an 840?





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Think Snow Eh!
Ox
 

triumph406

Titanium
Joined
Sep 14, 2008
Location
ca
Why not name them?

If you get shit service and support, I think others would appreciate to know who to avoid, or be cautious of.

and if the service is good, wouldn't they also like to know? I'd like to know.

It sounds like they're trying to make things right for you. Why not tell us? Not everybody has stellar service and support these days. I'd rather have a less capable machine as long as it is supported and I can have a technician out in a timely matter should there be a problem. A more capable machine isn't too capable when you have to wait weeks for parts or service, should there be a problem.

Might be safe to assume the vendor is aware of this thread and part of the agreement to swap the machine is that their not named. Cos' in all likely hood if their named a few here will jump on the "I had a crap machine from them too" bandwagon. Maybe some significant issues, or the usual "I'm running my coolant at 5%, why are the way covers rusting on my XYZ machine?" complaints

The moral of this story is if you complain about the poor performance of a machine without naming and shaming it could likely be resolved in a civil and responsible manner. Especially if your civil in your approach here (PM) or with the machine builder.
 

thesidetalker

Hot Rolled
Joined
Jan 11, 2015
Location
Bay Area, CA
Might be safe to assume the vendor is aware of this thread and part of the agreement to swap the machine is that their not named. Cos' in all likely hood if their named a few here will jump on the "I had a crap machine from them too" bandwagon. Maybe some significant issues, or the usual "I'm running my coolant at 5%, why are the way covers rusting on my XYZ machine?" complaints

The moral of this story is if you complain about the poor performance of a machine without naming and shaming it could likely be resolved in a civil and responsible manner. Especially if your civil in your approach here (PM) or with the machine builder.

Perhaps. You might be right about an agreement. Although no harm in the OP replying so if that is the case.

You also might be right about the bandwagon, but to me that wouldn't necessarily sway my opinion one way or another. It sounds like the mtb is trying to make things right. Although it's not clear whether they were going to replace the machine on their own accord, or only acted so if the OP threatened to smear their name here? I also wonder what the timeline is for all these events? Maybe I missed it

Hopefully the new machine leaves better finishes.
 








 
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