# Rough Running Milling Machine



## Pete92 (Jun 25, 2013)

Hello,

A few years ago I purchased a SPG tools milling machine (SPG9525). Since then it has been nothing but problems. Mainly with the quill. 

It has always sounded rough when running and caused a lot of chatter. A look into this showed that the spindle was running out by about 2 - 3 thou. This was then sent back to the supplier and re ground. I thought this would have done the trick. But it still sound very rough and seems to knock.

Can anyone suggest where is next to take a look at. I was considering looking at the gears but wouldn't know what to look for to be honest. And would this cause chattering?

My plan is to convert it to CNC control, but I am unwilling too while its in this state.

Cheers,

Pete


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## Canman (Jun 25, 2013)

Hello Pete
I would possibly start and look at the bearings if the bearings are cheap and nasty ones their tolerances are not as tight and this can cause your chatter issue also if a bearing has collapsed or just spat one bearing out it would work but be very rough sounding. I had the same problem with a Bridgeport at work. 
I hope this gives you somewhere to start. 

All the best James.


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## rcfreak177 (Jun 25, 2013)

Canman said:


> Hello Pete
> I would possibly start and look at the bearings if the bearings are cheap and nasty ones their tolerances are not as tight and this can cause your chatter issue also if a bearing has collapsed or just spat one bearing out it would work but be very rough sounding. I had the same problem with a Bridgeport at work.
> I hope this gives you somewhere to start.
> 
> All the best James.



Yep I would be looking at the above post,

Also might pay to check the fit on the bearings to the spindle shaft and the housing, If they are not a nice tight (light tap in fit)  they can spin causing the ball race to stay still, I had this problem with a spindle I made, once spun up it made all sorts of funny sounds and became hot quickly.


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## rodw (Jun 25, 2013)

Maybe check bearing preload. Put an indicator touch the bottom of the quill and see how much movement there is if you press up on the quill. There should be none. The book I followed when I rebuilt my last lathe said something like tighten to remove any play then go 1/8 of a turn further. Run for 20 minutes and check bearings are not hot. If they are, they might be too tight. Anyway, something to guide you by as it is all similar construction.


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## velocette (Jun 25, 2013)

Hi Pete
A few more thing to consider on your mill running rough.

From a little research on this mill type I see it to be a gear driven spindle with an extending quill.

As canman points out that less than satisfactory bearings can be the problem.

Replacement bearings and properly setup will go along way to improving it.

Careful adjustment of the gib strips on the mill head "Z" axis combined with adjustment to the table gibs "X and Y" axis will help to minimize chatter.

Some of the noise can be from the quill spindle not running true in the splined drive or lack of lubrication on the spline.

The Knocking you mentioned can be from the change gear with an excess clearance on the bore and clanking on the key driving it. 

All this points to a strip down check and overhaul to fix it not an easy solution but worth while when you have a mill that you are satisfied with.

Be proud when done and can say I fixed it

Eric


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## Pete92 (Jun 26, 2013)

Hi folks, 

Thanks for all the helpful replies!

I think it may be time to take it to bits tonight and see whats happening in there, and hopefully have more to tell you tomorrow.

Cheers, 

Pete


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## Pete92 (Jun 26, 2013)

Right, A quick dismantle tonight showed a few bits. 

Upon lifting the motor and mount off, the drive gear was still sitting on the top of the mill, so that has now been re attached and stud locked on. 

I have attached a video of the amount of play when turning the spindle. There is quite a lot of backlash. But on taking the motor off and disconnecting the gear chain, the back lash is still there in the quill. Its quite hard to explain, but the when the main spindle bearing is static there is still play in the spindle. I have attached a couple of videos to help explain.

View My Video

View My Video

Does anyone know how to get into the main head of this? 

Cheers,

Pete


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## canadianhorsepower (Jun 26, 2013)

Pete; I don't know if you have this, but this is the same machine you have with a different name tag
http://www.busybeetools.com/product_manuals/CX600.pdf
parts 6,7,8 take care of your bearing lash  and
60,61,62 total lash of the column

hope it helpThm:


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## Pete92 (Jun 26, 2013)

Ah right, that's a great help At least I don't have to pull the head off like I though I would.

What tricks can I do to get rid of the backlash in the gears? 

Cheers

Pete


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## velocette (Jun 27, 2013)

Hi Pete
Do not worry to much over the backlash in the gear drive. Each pair of gears has to have running clearance plus the sliding clearance on the quill.

Please keep on posting your progress 

"What cheor geordie"

Eric


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## Pete92 (Jun 28, 2013)

Hi, 

Did a bit more last night. Stripped down the quill and rebuilt it. 

Still sounds quite rough, but after running for 10 mins or so the bearings we quite warm, so ill slacken them off tonight.

Ill let you know what happens.

Cheers,

Pete


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## Pete92 (Jun 29, 2013)

Right, mill is fully back together, Clocked every part of the quill in on the lathe and it all seems fine. So greased up and back together.

Seems to be running slightly nicer. Havent tried a cut yet.

Ran it for 15mins or so today, bearings were slightly warm. Is this an issue? or just them bedding in? 

I think I may convert it to belt driven drive.


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