2017 POTD Thread Archive

bobshobby said:
It looks like quite a nice little dividing head how many teeth on the worm wheel. You say you had problems, but what were they, and how did you solve them. Maybe we can all learn here.
Bob.
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First was the spindle. I cut the worm threads too deep on the original spindle/shaft. Broke in two when I was handling it so had to machine a new spindle. The centerbore on the new spindle has a thicker wall. Then the lock for the spindle did not work when I put the wormshaft in, they were too close, so I had to move the locking lever to the other side of the dividing head and flip the locking piece. I had to "lap" the shaft and lock mechanism to get the fit right. That's not so much a problem as its a normal process of machining the project. Now I have the degree 'defrugaltie' to resolve. Mostly minor when you take them alone but revealing about my methods when taken together. But "Hey!" I'm doing what I like to do. The frustration is minor compared to that.
:hammer:

I do actually sketch out most of my projects. That avoids some of the type of 'defrugalties' I ran into on this one. But sometime I think I don't need to do that and find out I do. So somewhere in the near future I will make a sketch/CAD drawing, to try and catch all the possibles that may still come up as it progresses.

Whyemier, revealing all his deep dark secrets and inadequacies.
 
mksj said:
This was a project I helped Firestopper (Paco) with, since he is recovering from surgery. It was a bronze base for a roulette wheel that the top had been distorted and then cross threaded by someone else in an attempt to get the top spinner to thread onto it. The base had a 1"-16 pitch thread, but was pretty badly mangled, the fix that we came up with was to return the base and upper structure and cut a new 15/16 male thread and a corresponding female thread in a bronze fixture that was a press fit in the spinner head. I chucked up the base and turned all the matins surfaces on the base then flipped the base and turned down the neck of the base. Then cut down the threads to the major diameter of the 15/16 thread and aligned the thread cutter to match the residual groves of the existing threads.

The female threaded fixture was ~1.27" OD bronze stock that was machined out to the minor diameter of the 15/16th internal thread. Now the challenge was that my internal threading tool holder that I have has a 11 IR A60 insert, suppose to be good for 16-48 pitch, WRONG. I guess it is all relative, a 15/16 - 16 calls for around a 0.07' thread depth, the 11 IR A60 can only cut something like 0.045 deep. So I improvised, I cut as deep as could with the threading insert holder and followed it with a recondition (eBay special) 15/16 bottoming tap. It would have been to deep a cut to take with the tap alone, and I also needed it to have minimum TIR and run true.

The final assembled base/support and nut had a TIR of 0.001" at about 8" out, and pressed in nicely to the spinner assembly. The proceeds of the job went into getting a new internal holder that takes a 16 IR AG60 insert that can cut a 8-48 TPI to a depth of around 0.07". So I learned something new about internal threading/inserts and using BIG taps. I also used my proximity stop system to cut both the external and internal threads to a fixed position. I have been cutting threads for the most part with the compound locked and only using the cross slide, which assure a repeat positional accuracy of better than 0.001" with no play or wobble. Always learning new tricks. That the fun of it all. Thank you Firestopper (Paco) for your guidance and assistance.

Base after being trued up and threads being turned down, and turning the female threads.
View attachment 143056View attachment 143053
Finished.
View attachment 143054

View attachment 143055
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Here is the finished roulette wheel, it will be converted into an end table with a glass top with a hole (for spindle) allowing the roulette wheel to spin while setting items on table top.
It ran true as mksj did a outstanding job salvaging the item and machining a new bushing. here is a text the customer sent of the finished item. Thank you Mark!
fullsizeoutput_539.jpeg
 
bobshobby:

Turning insert nomenclatures are typically ANSI/ISO standards. The letters are in a first, second, third, and forth position to describe the insert 1) Shape, 2) Cutting edge angle (clearance angle), 3) Insert IC and thickness tolerance, 4) Insert topography and if the insert has a hole in it and the hole shape. (is the hole cylindrical or does it have a shoulder and what is the shoulder angle so one uses the proper screw) Always watch for a letter "X" in the insert letters since "X" is a Wild Card and un-defined. Milling inserts however, look like alpha-numeric soup and are all over the map due to the many design features. For those details, you need to do a little work and consult the manufacturers literature.

Best Regards, Garyy
 
G MORSCH said:
bobshobby:

Turning insert nomenclatures are typically ANSI/ISO standards. The letters are in a first, second, third, and forth position to describe the insert 1) Shape, 2) Cutting edge angle (clearance angle), 3) Insert IC and thickness tolerance, 4) Insert topography and if the insert has a hole in it and the hole shape. (is the hole cylindrical or does it have a shoulder and what is the shoulder angle so one uses the proper screw) Always watch for a letter "X" in the insert letters since "X" is a Wild Card and un-defined. Milling inserts however, look like alpha-numeric soup and are all over the map due to the many design features. For those details, you need to do a little work and consult the manufacturers literature.

Best Regards, Garyy
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Thanks,

Alphabet soup, that's what I was worried about. I'll worry about it in more detail when I need to.
I didn't even realise that milling inserts would be different, but I guess they would need to be more tolerant of intermittent cuts. Especially on fly cutters.

Bob.
 
Billh50 said:
bobshobby'
here is a link that will help identify carbide inserts.
http://www.carbidedepot.com/formulas-insert-d.htm
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Thanks Bill, Your wide knowledge is amazing. I will have to study the charts. I've got 5 or 6 tools with insert tips on them I'll see if it makes sense

It's a long way from what I use to know when you just took a piece of HSS and ground it up to whatever you wanted.. And I've still got a box of them from way back when.

Bob.
 
Billh50 said:
Bob,
I am good at finding stuff for others. That's why my friends always ask me to find stuff. I just wish I could find stuff for myself as easy. LOL
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If that's the case Bill create an imaginary friend that lives next door and find a low cost mill for him, and then when he can't be found it's yours.
 
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