Tube Polisher....

[JimDawson]

I got a bit more done on the tube polisher today. The belt drive wheel shafts.



These are about 5'; long, and the raw material is 1.5 diameter 1018 steel. I had some 1 7/8 shafting in the shelf so I decided to use that. The biggest collet I have for the lathe is 1.5'' so I had to turn the 1 7/8 down to 1.5 on my manual lathe.

This was made in two operations, the gray outline on the right side of the picture, then flip it over and use a 1'' collet and machine the left side in the second operation.



I was going to do these in the manual lathe, but the CNC lathe was just sitting there doing nothing and I had the needed collets. Besides, using the CNC will make both parts exactly the same, and make even me look like a machinist. Honestly, I have never claimed to be a machinist, I really don't enjoy making chips. I'm a problem solver who sometimes uses machine tools to facilitate providing a solution.

To keep the Z 0 in the same place for both parts, I set up the collet stop. This also required that I face the raw blanks to the same length, I did that in the manual lathe.



And set with about 3.375'' sticking out of the collet. This will give me about 0.100'' tool clearance from the collet.



Tool clearance at minimum Z travel



It took me about 45 minutes to set up for the first cut and get it dialed in. Then 6:45 to turn the first end. All I had to do for the second part was to put the raw stock in and press Go. 6:45 later I had the first end completed on both parts. I don't care how good the setup is, or how stable the machine is, cold rolled shafting always comes out looking like crap. The surface on the left was just rough turned at 160 FPM on the manual lathe without coolant, and the right side was turned on the CNC at 300 FPM and flood coolant. The surface finish looks the same.


It took me about 5 minutes to change the collet and setup for the other end, and about 4:45 to run the part. Just needed to move the collet stop to the 1'' collet and reset the Z 0 position.

And two nearly identical shafts, and didn't have to stand over my Jet lathe for 3 hours to make these.



With the gear in place.


Now I only need to drill & tap the end, 1/4-20, and cut the keyway.

 

[Papa Charlie]

I designed a machine for making metal screen printing frames for a screen printer. He came up with the concept, I designed the machine to make it a reality. Worked great. He used it for some time and then a company that made screens bought it from him along with the concept. Made out very well.

Sadly they disassembled the machine and were never able to reproduce it or to reassemble it and make it work again. A much more precision machine to get frames that were perfectly flat for the light weight screen printing machines to produce perfect images.
Point is that it takes a lot of working parts to make a machine work and work properly. People don't realize what it takes to design and execute the build to have it actually work.

Bottom line, very nice work. A lot of details and parts to produce but will be well worth it when you get done. Along with being something that you can be proud of. Of course your business will benefit from this, but who knows where it may lead.

 

[JimDawson]

People don't realize what it takes to design and execute the build to have it actually work.

Thank you for the kind words.

The setup and spindle time on this machine is a fraction of what I have spent on design. I would guess that I have really only spent about 3 days on setup and actually making chips, so far. I'm just not as fast as I used to be, and can only handle about 4 hours of shop time / day.

 

[extropic]

Hey Jim,

It's looking very good. The belt drive shaft assemblies look very robust.

I'm curious about the pinion gears. How did you procure the pinions? Are they available as discrete parts (at an auto parts store?) or did you have to buy complete Bendix assemblies to get them? Or???

 

[JimDawson]

Thank you!

I bought the complete Bendix assemblies. Standard small block Chevy gears. I looked for just the gears, but was unable to find any.

 

[JimDawson]

It's been a bit too hot to work in the shop for the last week or so, I spent most of my time sitting in front of my fan in my underwear

Moving right along, today was the day to get started on the main axle shaft.



And an assembly view


So start out with a 4'' dia. x 6'' chunk of 4140.


And spend half a day chewing on it to get it down to 2.952 OD.



Now comes the fun part, threading the end. The nut is M75x2 but I'm too lazy to change the gears in my lathe to cut metric threads. So Imperial threads are going to have to be close enough. I have done this successfully many times before. A bit of math: The nut thread pitch is 2MM = 0.0787'', so 1/0.0787 = 12.706. My lathe won't cut a 12 3/4 TPI thread, but it will cut 13 TPI just fine. 1-(12.706/13) = 0.023 = 2.3% error. Close enough.



The nut screws on smoothly with no binding, and no perceptible looseness, a very good fit. If you didn't know what the thread actually is, you would never know the difference. The fit is done by the cut/try method, take a cut, try the nut, take another 0.001 cut if needed. Rinse/repeat until you get a good fit.

Every project deserves a new tool or two, it really doesn't matter if the tool has anything to do with the project or not. But in this case I did need some boring bars. All of my carbide tipped bars are getting a bit tired. I have never used insert boring bars before, so I thought I would buy some.

So I bought one of these https://www.amazon.com/ASZLBYM-Internal-Turning-S20R-MWLNR08-Indexable/dp/B07Z9XZNX8/ref=sr_1_1?crid=3FUQEDOOWYVLK&keywords=ASZLBYM+3/4"+Lathe+Internal+Boring&qid=1659501928&s=industrial&sprefix=aszlbym+3/4+lathe+internal+boring,industrial,154&sr=1-1


And this set https://www.amazon.com/OSCARBIDE-Indexable-Carbide-Inserts-TCMT21-51/dp/B07SHC6H73/ref=sr_1_3?crid=ZDGLG4ZYNOZV&keywords=OSCARBIDE+3/4"+Shank+Indexable+Boring+Bars&qid=1659502058&s=industrial&sprefix=oscarbide+3/4+shank+indexable+boring+bars,industrial,163&sr=1-3



Should have them in the morning. We'll see how they work out. I suspect the published dimensions on the set is overall length rather than the stated cutting length, and if that's the case, I'll have the longer bar to reach the needed depth.

More tomorrow.

 

[Papa Charlie]

Looking good. A lot of material to remove on the axle, that is where a large machine can shine. Great work around on the threading. I would not have thought of that. Sadly, I will not be able to unsee the image of you in your underwear in front of the fan

As for the heat though, I am with you, I melt at 75 degrees, PNWer. I designed a case neck turning base for my 21st Century head and tail stock. A friend let me use his Tormach 1100 last Friday, with his supervision as I am just learning CNC. Tried to get it done before it got too hot but with all the instruction he went through teaching me and BSing, it was 2PM by the time we were done. Too hot to be in the shop but really appreciated him taking time on his day off to help me out.

While I love the older heavy machinery, got to admit, CNC is a lot of fun and opens up a whole lot of opportunities.

 

[JimDawson]

Looking good. A lot of material to remove on the axle, that is where a large machine can shine. Great work around on the threading. I would not have thought of that. Sadly, I will not be able to unsee the image of you in your underwear in front of the fan

As for the heat though, I am with you, I melt at 75 degrees, PNWer. I designed a case neck turning base for my 21st Century head and tail stock. A friend let me use his Tormach 1100 last Friday, with his supervision as I am just learning CNC. Tried to get it done before it got too hot but with all the instruction he went through teaching me and BSing, it was 2PM by the time we were done. Too hot to be in the shop but really appreciated him taking time on his day off to help me out.

While I love the older heavy machinery, got to admit, CNC is a lot of fun and opens up a whole lot of opportunities.

It is times like this that I wish I had a bigger lathe. My little 13x40 is a bit taxed by jobs like this. But persistence pays off, just take reasonable cuts at reasonable feeds and speeds and the job eventually gets done.

Welcome to the world of CNC. When my son introduced me to the world of CNC it changed my whole perspective on machining, and the real up side is that it makes even me look like a machinist.

 

[rwm]

"My little 13x40"
Hysterical to many of us!

 

[Aukai]

Jim gives an accurate description though, my 13 x 40 is much better than the 1228, but mine is not an animal for hogging material. It does get the job done.