Vibration in X 1996 VFOE

[hend.engineering]

Hi,
It's been an issue probably since I bought the machine 3 years ago but has only come to light as I've tried to be more ambitious with it.

Esentially, 20mm end mill, 36mm DOC 2mm width of cut, 4FL in steel. 250m/min Vc 4000rpm, 2.8m/min cutting speed. Mild cutting data for what the tool is capable of.

I set up a rectangular block of mild steel in the Kurt vice to test, vice aligned to X, so jaws along Y.
Cuts quietly in Y, sings like a long overhanging boring bar when cutting in X.
Noise reduces with RPM and feed override as you might expect.

My assumption is that it's worn linear guides, am I barking up the right tree?
Some head nod / wiggle perhaps.

The longer story is that I had a pair of guys around from ZCC cutting tools who have been happy enough to let me have and test a few of their cutters. We went at it and although it started well, and the cutter put up with it admirably, the noise in the X direction was deafening. We slowed it down but basically the only way it worked was with a 1/4 of the tools cutting capability.

 

[countryguy]

Been here, Seen this, and there are several items to review and check as I see it.
a) the table push and backlash tests.
b) folks post on things of this nature and some common terms you mentioned which made me thing of my thread link below (which I started).
c) Rails and screws ...sure could be. have you pulled the way covers and dug in under the covers? Someone noted to me- Move the vise around and see to help determine if positional? (worn screw spot. Rail issue/trucks. ) ? Honestly, we never did did in and fix is to 100%. He ended using a different machine to complete that job. There are folks who talk about Servo tuning and other elements.

As we all know here. . It's trial and error sometimes. So this is a DC Brush unit then. and the Spindle, Belt drive or gear? Have you ever replaced the Drawbar? Or done a drawbar test? We ended up getting that done and it's helped in some ways w/ P&A and cutting quality, Did not solve this issue though (to be clear). We also did a spindle reground too at the same time (best $600 we spent on our 98 VF imo) Tool-holders and holder quality? You have some decent holders? On calls, so just passing the things we ran around with.

10sec Vid inside - VF X travel squeal back side only... Kid trying to solve.

Issue: Bad squeal and chatter on backside of different parts and different sizes. Always on X travel, back side, traveling to left, (X-) 10sec vid: https://youtu.be/Rqt0-BDrHa0 Detail: The Son is on his first big PO! (whoot!!!) A36 and 1020 steel. Imco cutter, 1/2 OD, I think they call...

www.practicalmachinist.com

power-off table pushing tests in X. should it move? Tens backlash w/ power-on

Having a brain freeze.... We are dealing w/ some vibration issues in X and been rooting around. The power-on backlash text is a ten. It seems really tights. We had completed the thrust bearing cartridge and end bearing last Winter. Now, With power OFF, the Son pushes on the table in X...

www.practicalmachinist.com

 

[hend.engineering]

@countryguy

Hi, and thanks for all that. I worried my question wasn't going to get a reply!

I'm relatively new to cnc, 3 years I've had this Haas now, and so I'm not fully up to speed on what to check and look out for.

I dismissed the spindle taper as an issue since it was only an issue in one plane. I was using a year old hydraulic holder, and tend to avoid cheap collet holders after I realised the surface finish improvement I could get with hydraulics and shrink fit.
I shall have to check the draw bar. Blue test on taper reveals some imperfection, but I'm not sure quite how to judge it. From memory contact was good at base and top, and maybe a bit vague in the upper centre. Tool holders stick occasionally if worked hard and or left in the spindle for a while, so my guess was that it isn't tragic.

Noted on table test and vice position. I tend to centre everything which is probably not ideal, so I'll do my test piece on the ends and judge the results from there.

When I home the machine on startup the screws don't sound amazing, but having said that I've never worked another Haas to know any different.

I had the covers off a few months ago and aside from some swarf build up it wasn't as horrible as I was expecting, screws turned ok, no notchyness, so maybe it's the motor noise. I didn't check the thrust bearings, maybe I should have but I was only trying to find the possible lubricator leak at the time!

I'll report back next week.

Thank you!

 

[EMTech]

If the homing also sounds rough, I would suspect a bearing pack and/or the ballscrew...

 

[hend.engineering]

Using my 10th gauge I thought I'd set up a quick experiment to gauge the situation.
Power on, homed, and mid table I can give it a good tug and measure about 6 or 7 tenths, but it always springs back to zero. Seems about the same in both directions.
Power off and can pull the bed back and forth, I wouldn't say it was easy but it is doable.

Thoughts everyone?

 

[EMTech]

Not great, but not the worst I've seen on a Haas.

The only way to know for sure is take some way covers off and find the noise.

 

[hend.engineering]

Not great, but not the worst I've seen on a Haas.

The only way to know for sure is take some way covers off and find the noise.

Ok, thank you. I shall have a nose this week and see if I can isolate the issue!