Milling question - surface finish

I've got a Warco round column mill 3/4HP motor and belt driven. Given that I'm using a sharp cutter at appropriate feeds and cutter speeds, what causes a poor finish when up or down milling with the side of the cutter?

Need to talk to speak to Warco really, but just maxed out during "normal" working hours.

From the trouble shooting guide:

"Shack of spindle and roughness of working surface has taken place during performance" - seems to describe the problem.

So I put the DTI on the collet chuck and whilst I can cause a deflection on the indicator, I can't find any "slack" or "shack" for that matter.

The guide has a couple of options on adjusting the spindle bearings which I can't decipher:

a) The gap of the spindle bearing too wide - Adjust the gap in proper of replace bearing with one.

b) Spindle loosening up and down - make two of inner bearing covers on the top tight each other. Do not overtighten two innner bearing covers with the taper bearing; It is OK as long as no gap between them.

Is it worth knocking out the chinese bearings and replacing with a couple of quality jobs from Ketan?

Steve

Reply to
Steve W
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Steve Hi

I really will have to stop using Google to access this as your post although several days old has just appeared on my PC. Although I've recently sold mine I had a RF25 for many years and it worked well, you don't say which machine you have but your quote is classic RF 25/30, "Complex Machine" instructions.

Many issues can affect the surface finish on the mill and I would check the adjustment and set up before taking it apart and changing the bearings. While I did clean out my bearings and re-adjust the pre- load several times they worked OK for me for about 8 years and still seem fine. The pre-load is adjusted by the two locknuts which are accessible behind the information plates on the front of the head. The lower nut adjusts the pre-load and the upper just acts as a locknut. I found the best way was to adjust the lower one until there was no slack (shack) and then hold it and tighten the locknut on to it. This increases the load slightly and should be just right. Take care to check that the bearings are not heating up with the machine running at full speed for a few minutes, if so back off the adjustment slightly. The other issue with mine was that there was a lot of sand/swarf etc that needed cleaning out of this space as I didn't want it to contaminate the bearing grease. Although as I said I did strip and clean/re-lubricate the bearings they didn't really need it, proper adjustment would have been fine. I'm sorry but it was so long ago I can't really remember the exact detail of how it came apart.

On mine, I had more of a problem with the table gibs being a little loose when supplied (not by Warco). I would check and adjust these regularly they are easy to do. I don't really understand how you are taking the cut but make sure you have locked all slides other than the one direction you are using. The downfeed is particularly prone to some backlash and it took me a little while to adjust the little setscrew to get it just right for boring or initial slot drilling. I always tried to take the cut from the edge of the work or at least with the downfeed securely locked after it had reached the required depth.

If you haven't found it yet there is an excellent mill_drill group here:

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There are several versions of the manual in the files section and if you search in the messages you will find a number of posts on spindle adjustment.

Hope this helps a little, best regards

Keith

Reply to
jontom_1uk

Thanks Keith. I registered on the site so can't get access to the files and photo's until the membership is sorted. There is a post that suggests the chinese drive belts can have a significant effect on finish. I think I'll take your advice and start making certain the gibs are set properly, didn't think to do that.

I bought the machine new from Warco and it was "clean" when I received it - no sand from the casting left in the head! It's the "Economy" mill which is an RF25 type machine. I added a digital scale to the z axis over the weekend and that helps a lot, I felt that the feed was a bit uncertain and the digital scale has exposed the problem - when I set a depth on the dial index, locking the quill adds a thou or so for good measure!

Reply to
Steve W

Steve Hi,

I completely forgot to mention what a difference a digital scale makes on the z axis, like you it was one of the best additions I ever made to the machine. I've heard of others having problems with belts, sand, poor bearings etc but to be honest other than a little crap in the housing mine has been fine. I did try one of the link belts for a short time to see if it made any difference but I didn't notice any real improvement; for me it was just a case of ensuring everything was properly adjusted. In the early days the machine seemed to take a while to settle down and I checked the adjustment quite often, but after a few hours (maybe 50 or so) use then all stabilized. I checked things every few months or so then but little adjustment was required over the last few years of use.

Regards

Keith

Reply to
jontom_1uk

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