This Mornings Machining Project

Tarry, the gears are case hardened, about .060-.070" deep, the outer casing is probably around 58-60 on the rockwell C scale. Darned hard, once you get thru that it is just tough material, kind of like machining 4140. I suspect that it is sae 8620 which is what most modern gears are made from and induction heat treated. The insert in the picture is just a generic that was worn down. I think it is a Kennametal K68 general purpose (C3) TCN insert. You can also use K313 inserts (C3-C4) in its place. The main reason I use these is because I have 2 small fly cutters and several lathe tools that use the same insert. I have been finding these on Ebay and local flea markets. They are generally cheap compared to most others. There was no real reason for the 7* other than they were available easily and I have use for them in multiple tools. The 11* is little more fragile on the edge of tough material but does leave a better finish if the material is not to tough or hard. Sometimes its a crap shoot and you need a little finesse to get the job done. I have them in both .016" radius and 1/32" radius tip. I also grind a chip breaker on them with my diamond wheel as needed and hone them with a diamond or ruby lap. The one pictured is a 322 series insert. 3/8" inscribed, 1/8" thick and 1/32" radius. I do run these a little faster when boring to help with chip breakage, I do not generally use lube with carbide, I do use water soluble sometimes if the part is getting to hot. In the real world you would rather the chip be blue, that means its carrying the heat away from the part, and not keeping it all in the part your working on.

 

I know where the gear came from.....

 

I can do nice sturdy fabrication, I can weld well and work heavy equipment well and build fairly nice, utilitarian stuff. Looking at your guys' conversation though makes me feel like the kid standing there saying "I ate a rock."

 

The gear you machined for me worked great! Thanks again!

 

Your welcome!

 

Well today I had another project, actually 2 of them. One was to replace the damaged stud on a brake pedal arm, the other was to bore out another brake arm that had a wallowed out hole and put a bushing in it.

 

Beautiful work Mike! It was very nice meeting you/talking with you the other day!

 

I haven’t forgot you Ryan, working on your fitting today. Was great getting to talk to you also.

 

Can you please, give us mortals the part number of the sealed cone bearings? Thanks!

 

Looking at the part numbers Timken LM11710 / LM11749 I don't see A sealed version of this assembly.

For A bell Crank with tapered roller bearings try.

1 st Gear Off-Road-Products
1247 S. Buena Vista
Unit -C
San Jacino Ca. 92583
Phone 951-654-4532

 

I built a ball turner/radius cutter for my lathe awhile back. I had not finished it until today. This fixture is for turning radii on the corner of parts or turning a ball shaped object. I can adjust the size in .001" increments up to 1.000 radius. I needed a ball shaped handle for the turner so I used the fixture to turn the handle for itself. This little fixture actually worked quite nicely and I was impressed by the finish it left. The machine finish was good, I buffed it with rouge to shine it up before installing it on the fixture handle.

 

How are you holding the piece down?

 

Are you talking about the fixture on the lathe? It is locked into the cross feed compound. The older South bend lathes used tapered round wedges in holes on the side of the compound, they are locked down with set screws in the sides of the compound.

 

Actually I was referring to the boring of the pedal arm.

 

Ok, so the holder for the carbide insert can move in and out to made differing radius jobs. What holds it down? The entire fixture can rotate? Does it do this manually with the arm and the ball you made for it? Do you just rotate it by hand? How did you made the fixture ridged enough to stop chatter? This is really cool.

 

The stud on the pedal arm is clamped in a V block. The pins and spacers help keep it from twisting.

 

There are 3 set screws in the side of the round base that clamp against the sliding portion. The base is clamped with its dovetail in the saddle. The upper round base is built with .0007 clearance for movement and is held together with a flat head in the bottom. It is so smooth with the grease in it there is no movement up and done.