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JoeLee
03-23-2017, 05:39 PM
I made these two rings to cut the weight segments out of for my balancing hubs. I measured them to the tenths on the ID & OD.
After I cut the first ring from the bar I noticed when I put a ground parallel across the faced end that it had moved. The inside edge raised slightly in a few spots. I could also feel it move when I set it on the surface plate.
I've had this issue when making similar parts out of steel but didn't expect it to happen with 932 bronze.
The rings also went out of round by about 1.5 thou. None of this will matter since the weight segments won't be much longer than a 1/2" but what if it was something that did matter like a bearing or sleeve.

Now I have to face the opposite side down to the appropriate thickness.
Lastly............ what do I do with the 3 Lbs. of turnings?????? Hate to scrap it. Maybe I can melt it down into something useful like a piece of bar for the next project.

JL................

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rkepler
03-23-2017, 08:37 PM
Everything moves and/or is made of gum rubber. Cast stuff moves the most, When machining something cast I usually rough things in and leave it overnight before finishing, and even then I've seen cast iron casting move .006" across a 1.5" bore.

JoeCB
03-23-2017, 09:00 PM
As for the turnings... I do some considerable work in brass and bronze. I used to sweep and toss the turnings, no longer. Save all the turnings and scrap and it goes to the salvage yard, $1.10 per pound. Oh' be sure to thoroughly clean your machine of any steel residue before beginning the brass/ bronze work. If the scrap man's magnet picks up anything, you loose big on the price.

Joe B

Mcgyver
03-23-2017, 09:49 PM
I think you weill need more chips....but this cast apple is sort of neat....

https://www.youtube.com/watch?v=4pdjg3a1amM

JoeLee
03-23-2017, 11:28 PM
Everything moves and/or is made of gum rubber. Cast stuff moves the most, When machining something cast I usually rough things in and leave it overnight before finishing, and even then I've seen cast iron casting move .006" across a 1.5" bore. It didn't move until I cut the ring from the round. At this point it's not going to return to post cutting dimensions. In this case it's not going to matter and I can't change the ID or OD.

JL..................

LibbyHillBrewer
03-23-2017, 11:28 PM
I'm told that swarf doesn't really cast all that well because the metal has so much surface area that it tends to oxide heavily at melting temperatures and you lose a lot to slag. That's not to say that if you had a lot of turnings you couldn't make up for losses by adding more to the crucible though.

The other problem is having a furnace that's gets hit enough to melt copper and bronze.

Sent from my SAMSUNG-SM-G900A using Tapatalk

Lowery Racing
03-24-2017, 07:03 AM
In my experience, bronze is the worst as it always moves, warps, twists in some form or fashion, fortunately is this case the pieces are still usable..

Very nice work on the entire project!

HWooldridge
03-24-2017, 08:46 AM
In the future it might help to run a raw block thru a heat cycle to normalize internal stresses.

If you want to melt down the swarf, put a cover over the metal in the crucible - like a layer of crushed charcoal. Helps cut down on the oxidation.

JoeLee
03-24-2017, 09:40 AM
It sounds like it's not worth the time and effort. I had thoughts of perhaps melting it down and casting a small bar that might come in handy for a future project. There may also be some steel swarf in the mix. I may be able to pick it out with a magnet but if I don't get it all I'm not sure how it will come into play in the mix. Will it separate from the molten bronze???
The other thought that occurred to me after watching the video of the guy casting the apple is I may end up with a lot of voids in the bar which would make it unusable in most cases. Not sure if it changes the strength or integrity of the material either, and I would probably use more gas to melt the stuff that it's worth.

JL.................

JoeLee
03-25-2017, 10:17 PM
Does anyone have any ideas on how I can fixture each weight segment after I rough cut each one out of the ring????

After I cut each segment out I would like to make sure each one is the same size and the angle cuts are the same.
I need some thoughts on how to set up to do this.

JL.................

RichR
03-25-2017, 10:30 PM
Does anyone have any ideas on how I can fixture each weight segment after I rough cut each one out of the ring????

After I cut each segment out I would like to make sure each one is the same size and the angle cuts are the same.
I need some thoughts on how to set up to do this.

JL.................

Center and clamp it to a rotary table. Run a thin endmill through it to make a cut. Crank the table 120 degrees, add clamps if necessary, and
make the next cut.

JoeLee
03-26-2017, 09:34 AM
I thought of this but I don't want to remove the chuck from my RT and go through all the set up. Got to be an easier way.

I can scribe the lines and was thinking of clamping the ring in the mills vise and slicing through it with an .020 slitting saw.
However this still presents an issue as far as getting the angles all the same and the length of each segment the same.

JL..............

RichR
03-26-2017, 10:44 AM
I thought of this but I don't want to remove the chuck from my RT and go through all the set up. Got to be an easier way.

I can scribe the lines and was thinking of clamping the ring in the mills vise and slicing through it with an .020 slitting saw.
However this still presents an issue as far as getting the angles all the same and the length of each segment the same.

JL..............

Then carefully chuck up the ring and make scribe marks 120 degrees apart. You can do this on the lathe or rotary table. Now you should be
able to clamp it in the vise and and line the scribe lines up with the slitting saw.

JoeLee
03-26-2017, 11:54 AM
Yes, that is the way I had originally figured I would have to go about this without getting too elaborate.

The other thing I was wondering about was how big or long should I make each weight?? I know that in this case it's not size that matters but the weight of each segment, weather they are all perfectly equal shouldn't really matter.
I do know that even one segment that is about 1/2" long is probably five times heavier than any 7" x 1/2" wheel could be out of balance.
But this is relatively new territory for me. I'm pretty much going by what I see in other manufactured hubs.

JL...............

garyhlucas
03-26-2017, 12:14 PM
Three pounds of chips, lots of actaul labor, elaborate setups, more tooling. Why CNC is making more and more sense for the home shop! About 15 minutes to draw this and program in CamBam, then watch it cut. I get it, you aren't in a hurry, but it is nice to finish minor stuff quickly so you do more interesting projects. CNC is getting cheaper all the time at a very fast rate right now due to the influence of 3d printers.

JoeLee
03-26-2017, 08:08 PM
I think this is the way I'm going to slice the segments off the ring.
I scribed the ring using my center gage. I spaced the scribe marks .625 apart on the OD. I'll use the parallel to line the scribe marks up as shown and bring the saw down until it touches the parallel. Once I cut one segment I can use it for a pattern for the others.


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JL...............

mattthemuppet
03-26-2017, 08:48 PM
I'd just cut them with a hacksaw and file them to suit, but I'm guessing that isn't the finish you're aiming for :)

boslab
03-26-2017, 09:31 PM
Nice job joe, a setup like that broke my last slitting blade, steel tube, went fine till it closed on the blade an bit a chunk out, I'm just lucky I guess, it was thick wall hydraulic tube so I should have guessed.
Mark

JoeLee
03-27-2017, 12:06 AM
Nice job joe, a setup like that broke my last slitting blade, steel tube, went fine till it closed on the blade an bit a chunk out, I'm just lucky I guess, it was thick wall hydraulic tube so I should have guessed.
MarkI've had stuff like that close up on me just as the blade breaks through. Mostly rolled tube. Most of the time it pops open, but I do remember having some SS sq.tube that closed up and popped the blade of my band saw.. However I don't believe there are any internal stresses waiting to be relieved from anything cut out of a bronze round.
Bronze has some self lubricity qualities so it shouldn't be an issue.

JL.............

RichR
03-27-2017, 01:23 AM
I've had stuff like that close up on me just as the blade breaks through. Mostly rolled tube. Most of the time it pops open, but I do remember having some SS sq.tube that closed up and popped the blade of my band saw.. However I don't believe there are any internal stresses waiting to be relieved from anything cut out of a bronze round.
Bronze has some self lubricity qualities so it shouldn't be an issue.

JL.............

Or you could tap a wedge of wood into the hole as a precaution.

Rustybolt
03-27-2017, 08:43 AM
Obviously stresses built up in the casting process. Maybe anneal it next time?
I had a lathe job once in bronze with aluminum in it. Take a cut on the OD and the OD grew a couple of thou. Chase that down and the las measurement was undersized.

JoeLee
03-28-2017, 05:46 PM
Nice job joe, a setup like that broke my last slitting blade, steel tube, went fine till it closed on the blade an bit a chunk out, I'm just lucky I guess, it was thick wall hydraulic tube so I should have guessed.
MarkYou were right.... that ring snapped shut on me when I moved the saw out of the cut. I didn't cut all the way through, left about .010 on the inside but the force of the ring wanting to close up was more than that thin amount of material could support. I tried to spread the ring by hand but could barely get it to open up so I cut the segment out with a hack saw and left my mark clear. I measured the ring after I cut the segment out and it closed up .020 on the OD.
The segment was a little tight fitting in the hub groove so I stoned the top slightly and turned a steel round to the dia. of the inside groove wall taking into consideration the thickness of the sandpaper and lightly sanded the inside radius of the segment. I got a perfect fit. I'll use that one for the master pattern for the other two weights.
I wonder........... perhaps I should have hole sawed the rings over and under sized out of a piece of 5/16" bronze plate and then turned the ID and OD. Not sure what kind of internal stresses I would run into with plate.

JL.....................

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rkepler
03-29-2017, 11:31 AM
On something like this I tend to make a fixture to hold the section and turn it individually. If you place 2 of them opposed to one another you can still check the inner and outer 'diameters' and they don't shift. But I mostly do this to reduce material usage.