Surface Finish Issues On 12x36 (long Post) + Kb Electronics Vfd Install

I dont think its anything bad with the spindle bearings, it really doesnt seem like that. Maybe try to snug them up just a little, see if there is any change? I've only ever seen one bad set of spindle bearings causing problems in my life, and it was every turn. What you have doesn't look like that at all. At least what I am seeing in the picture.

I will have to try some parts on a machine this week too. If you didnt have good results on another machine, I would say it could be too light of a cut or in the tool, .002" feed rate is pretty much just rubbing. Any time I get a mirror finish on a part with carbide, its a lot faster feed rate, and I don't use the triangle carbide inserts, never had much luck with them. But you said it worked fine on the smaller 9x20, but I also assume that one was a belt drive machine?

At a .002 feed rate, any time I do it with carbide, or really any tool, even HSS, I get tears in the surface and just a bad finish overall.

I just can't look at the pictures and decide if its really bad, or if its nowhere near as bad as I might think, I wish I could see it in person, so I can compare with a cut I'd take. When you have time, try the thing with the link belts, leaving it as loose as possible to get it to still turn OK. Just trying to eliminate that pulley. Or like I said we can swap them out, but the pattern looks to me like its a lot farther apart than one turn of the pulley.

Any way you can post a video of the cut in action?

I know a lot of people go to the 3 phase and VFD to get the Best finish. Lots of option out there, I am just thinking out loud here really, but if its something as simple at that pulley, thats easy.
 
Muskt said:
Here is a still of a piece of 6061 that I just cut.
It is approximately 7/8 in diameter. Ran at 700RPM and the finest (0.002) feed rate. The cut was with the TCGT insert.
Click to expand...

What was your DOC? Even with that sharp insert, a shallow DOC can make the insert skip on the surface, given a poor finish. Try a minimum of 0.020" DOC.

700 RPM is very slow for cutting aluminum with carbide. T6061 is recommended to use 650 sfm, which means 2900 rpm... bump your speed up to at least 1200 or 1400 rpm and you will get better results.

You have a more powerful machine, don't be afraid to push it a bit harder than your 9x20. Carbide likes deep cuts and fast speeds.

What is the tip radius of your insert? I would also say speed up your feed rate to 0.004 ipr.
 
I'll try some of those things tomorrow.

I have read about and tried many different inserts. I understand about getting aggressive with carbide. However, these TCGT inserts are designated for aluminum and are close to razor sharp--Seriously. I don't recall the radius, but it is pretty small. They are not recommended for steel at all; however, I have used them successfully with very light cuts and obtained extremely good results (on the little 9x20). I can't locate an actual pic of one on the web, & I had better not get caught sneaking out to the shop tonight. But really, after getting a part close to dimension, this insert will bring of a whisker that is "finer than frog hair". But I digress.

Thanks again,
Jerry in Delaware
 
The razor sharp inserts for aluminum do great with light cuts. I can pull tenths with them. Leaves a bright finish on aluminum as well. Haven't tried them on steel. May try some light cuts to see how they work.
 
wrmiller said:
The razor sharp inserts for aluminum do great with light cuts. I can pull tenths with them. Leaves a bright finish on aluminum as well. Haven't tried them on steel. May try some light cuts to see how they work.
Click to expand...

I settled on inserts for aluminum turning SS barrels and crowning. I tried and spent few bucks searching for the best combination till I finally settled on razor sharp uncoated inserts DCGT 32.51, or CCGT 32.51 for turning and VCGT 110302 for crowning. They are fragile, use cutting oil.

Here is a crown chucked up in the 6J set thru after cutting, unpolished.

20151019_185736.jpg




I use these inserts on Aluminum on my 9x20, as the OP mentioned on doing on his own 9x20, with great results.
 
Damn nice. The finish is nice but the parts I like are the super sharp edges. It's leaving almost nothing behind. Thank you for giving the info on the actual inserts you're using. There are so many out there.

I had a thought about what might be going on with Muskt's surface finish, mainly due to the change when putting tape on the belt but I'm no expert so I'm going to wait. I'm curious.
 
Here is a pic of the actual insert I have been talking about.
I should have shot one from the side, too---it does have a good clearance angle, thus contributing to its fragility.
DSCN2901.JPG


Jerry in Delaware.

PS. I am working on a short video--I am gaining more respect for the guys on YouTube who produce all the videos most of us enjoy.
 
Yea, the real bright and shiny ones. Those will slice your thumb in a heartbeat. Don't ask how I know this... :eek::rolleyes:
 
Yes those are the same exact inserts that I use too, they work really well. I just got about 5,000 of them in. Jerry, I will be in your area in about a week or 10 days, I can't promise anything, but I might be able to swing by. If you are located where your profile says you are.

But go ahead post the video if possible too, that might help a lot.
 
You must log in or register to reply here.
Back
Top