What causes his "Pock Marked" finish ??

[mikey]

Looks good, Gregg. Glad you got it sorted.

If you have change gears for your lathe, you can alter the feed rate. Not sure its worth it, though.

Im such a beginner !!

This is where we all start, Gregg, every single one of us.

 

[GreggC]

Looks good, Gregg. Glad you got it sorted.

If you have change gears for your lathe, you can alter the feed rate. Not sure its worth it, though.



This is where we all start, Gregg, every single one of us.

According to my chart I am at the slowest feed rate,
Guess I stuck with it.

 

[Ken from ontario]

Ken,
These are the bits Im using,
TCMT2151
Last number is a 1, very pointy.
Can I assume I should look for a 2 or 3 ??
View attachment 260968

Greggc, I'm not an experienced hobbyist so my only advice is to listen to those who have been doing this for years.
Mikey and Ray have given you great advice so far:

You can cut AL with HSS if you want. Either way works. For carbide, just use anything that has a point on it. Don't over-think when cutting AL anymore than you would over-think how to tear a piece of cotton candy off the cone.

 

[GreggC]

I've got a pretty good handle on it,
The piece looks really good and I learned a ton !!
Thank you all very much !!

 

[Ray C]

Ray,
Thanks for the advise,
Im in my garage with the door open,
I think Ill add a fan to move the fumes away even quicker.
Not so messy with just spraying the piece, not constant spray.
Im such a beginner !!

Oil burn-off from lathe/mill work is not outright poisonous but, repeated exposure will likely have ramifications in the long-term. Also, watch-out for the cummulative/combined effects of exposure to many different things such as solvents, welding fumes etc. And be mindful of your hearing and use ear plugs when things get noisy. Screeching cuts on a saw or the loud gears of a lathe or mill will damage your hearing if you stick with this long term.

Your cuts looked good and hope it was fun for you. Now get a micrometer or calipers and measure each end to see if diameter is constant along the length. That's the next thing to think about.

Ray

 

[crazypj]

I do a lot of 6061 and some 7075 plus a few castings. Due to the limitations of the cheap 3in1 I bought (pretty much paid full price as friend was getting divorced) At low speeds carbide isn't a good idea, I only use HSS as it's much easier to sharpen. 'Dry' cutting is a bad idea, you will get localised heat build up on surface and a lot of tearing. Depending on which size machine your using you may be better off just using a 'polished ' round nose roughing tool. It will probably chatter real bad when you get 1/4" deep but cuts around 0.100" should give a' mirror finish' using cutting oil or any light hydraulic oil. Majority of people use WD40 because it's easily available but I've always found it a pretty bad cutting fluid, even used engine oil works better and prevents build up on HSS tools. The only advantage I've ever seen with carbide tooling is alumunium doesn't 'stick' to it so easy but to be honest, I don't have ant machines capable of really utilising carbide tooling

 

[GreggC]

Oil burn-off from lathe/mill work is not outright poisonous but, repeated exposure will likely have ramifications in the long-term. Also, watch-out for the cummulative/combined effects of exposure to many different things such as solvents, welding fumes etc. And be mindful of your hearing and use ear plugs when things get noisy. Screeching cuts on a saw or the loud gears of a lathe or mill will damage your hearing if you stick with this long term.

Your cuts looked good and hope it was fun for you. Now get a micrometer or calipers and measure each end to see if diameter is constant along the length. That's the next thing to think about.

Ray

Hey Ray,
Thank you for the advice / concern in reference to health and safety,
I've spent the past 30 years as a heavy Jet Aircraft Mechanic working for UPS,
I am very well versed on this subject.
UPS pounds this stuff into our brains !!
Before today I was not using lube and had my garage door closed,
This afternoon I opened the garage door when using lube,
Plenty of fresh air.
I always use safety glasses or a shield and of course I have my Bose blaring some good Country / Western music !!
I took your suggestion and measured each end of a piece I just worked on,
I used a digital Vernier Caliper and measured both ends at exactly 1.095.
A least that part of my cheapo lathe is correct.

 

[crazypj]

1/64" is roughly 0.015", a lighter than 0.008" finishing cut will give better finish as the radius of tip is the only thing cuting but with almost 0.005" feed rateyou will have the 'shrp' edge between radii. A 0.004" finishing cut with 0.005" feed puts more of the rounded edge in contact with 'extra overlap' I know that's not a good explanation A 'whiteboard and dry erase marker would make it simple to explain, 0.015" circles 'overlapping' by 0.0047" per revolution