Most cost efficient way to get steel tire blanks?
Re: Most cost efficient way to get steel tire blanks?
Hmm, robust machine. Looks like my Monarch 10EE has its first job lined up, if my Taiwan 12" lathe can't do it.
Re: Most cost efficient way to get steel tire blanks?
I would not even attempt this process with the machines i have. just simply not robust enough.Harold_V wrote: ↑Wed Feb 26, 2020 4:19 pmThat's an excellent way to approach the problem, but it's not as easy as it sounds for folks who don't have robust machines. You're caught in a situation where a broad tool requires a lot of rigidity to withstand the forces involved, otherwise there's serious chatter that is difficult to overcome. That the grind of the tool, due to the radius of the cut, demands that the tool not be as robust as might be possible for cuts taken towards center, you're caught between a rock and a hard place.
Not suggesting that it won't work for light duty machines. Just that it can be challenging.
H
I am currently installing DOM tires on a Harper Mogul.
If it is not live steam. its not worth it.
Re: Most cost efficient way to get steel tire blanks?
The following may offer some reference for those wishing to try trepanning the center out of a steel plate. What is shown in the pictures is a A36 plate 1" thick 12" square. The corners of the plate were cut off so the plate would swing over the lathe bed and held in a 10" 4-jaw chuck. What I'm making is a die to flange the 1/4" thick throat sheet of my boiler so to fit over the outside of the front tube.
The first step was to center punch the plate and scribe a circle to the finished bore diameter. I left about 3/32" finish machine stock per side for the trepanning diameter. In this case about 8 1/2" diameter. Next was to drill and ream the center punched hole to 1/2" diameter. The plate was served up to the chuck and the chuck adjusted until the reamed hole ran true within a couple of thou. Next the cutting tool was ground. The grinding was much like a 3/16" wide cut off tool except the out side and inside of the tool are radiused to clear the diameter of the cut. A 1" plate is an awful lot to cut through in one set up. That is one of the reasons for the reamed hole. I ground the tool for a little more than 1/2" depth of cut. After the first cut, 1/2" deep, the plate was flipped over and re-centered on the same reamed hole and cut through from the other side. The second reason for the reamed hole is to put a 1/2" dowel in it held in the tail stock so that when the center piece is cut through it is held central and not allowed to flop around and possibly get caught on the tool or lathe then break something. It can be seen in the pictures where the two cuts met each 1/2" deep and the thin flange of metal left on the center piece.
The actual cutting process is rather slow speed and hand fed so to observe the chip formation and react to any chatter or tool grabbing. I think I was rotating the plate at about 75 to 100 rpm. It takes a fair amount of continuous steady tool pressure to make a continuous cut. A liberal amount of cutting oil was used. I find tapping oil works well for slow speed operations like this. I'd estimate it was less than 15 minutes for each cut.
There are many ways to machine things. This is just the way I've done it. I've use the same process in my Southbend lathe for thinner and smaller diameter parts using narrower cutting tools. I just happen to have pictures of making the boiler die.
Dave
The first step was to center punch the plate and scribe a circle to the finished bore diameter. I left about 3/32" finish machine stock per side for the trepanning diameter. In this case about 8 1/2" diameter. Next was to drill and ream the center punched hole to 1/2" diameter. The plate was served up to the chuck and the chuck adjusted until the reamed hole ran true within a couple of thou. Next the cutting tool was ground. The grinding was much like a 3/16" wide cut off tool except the out side and inside of the tool are radiused to clear the diameter of the cut. A 1" plate is an awful lot to cut through in one set up. That is one of the reasons for the reamed hole. I ground the tool for a little more than 1/2" depth of cut. After the first cut, 1/2" deep, the plate was flipped over and re-centered on the same reamed hole and cut through from the other side. The second reason for the reamed hole is to put a 1/2" dowel in it held in the tail stock so that when the center piece is cut through it is held central and not allowed to flop around and possibly get caught on the tool or lathe then break something. It can be seen in the pictures where the two cuts met each 1/2" deep and the thin flange of metal left on the center piece.
The actual cutting process is rather slow speed and hand fed so to observe the chip formation and react to any chatter or tool grabbing. I think I was rotating the plate at about 75 to 100 rpm. It takes a fair amount of continuous steady tool pressure to make a continuous cut. A liberal amount of cutting oil was used. I find tapping oil works well for slow speed operations like this. I'd estimate it was less than 15 minutes for each cut.
There are many ways to machine things. This is just the way I've done it. I've use the same process in my Southbend lathe for thinner and smaller diameter parts using narrower cutting tools. I just happen to have pictures of making the boiler die.
Dave
- Attachments
-
-