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2021 POTD Thread Archive
- Thread starter Gaffer
- Start date
- Joined
- Nov 14, 2019
- Messages
- 106
I was working on my mill, I was paying more attention to the set up then anything else. I didn't look reached up and flipped the switch into reverse. The end mill broke the second I touched the part, which is when I found out that I found A. I put the mill in reverse and B. that was my only endmill in that size. So I designed and milled up an idiot lock to keep me from doing the same thing again.
- Joined
- Jul 29, 2014
- Messages
- 2,848
The centering scope project is something I'd like...but too lazy to take it on. The extremely high price of the edgefinders (tasters) depressed me, then I saw a wireless video camera system that would mount on the spindle and show the one point that does not rotate, the true center of rotation. This also was very expensive, in the range of the tasters. Then I saw an eBay ad for a $20 Spy camera, battery operated, WiFi, and shaped just like something that would fit on an arbor. Bought it, made a quick arbor for the mill, and tried it out.
First, the instructions are absurd. I'm ready to go decode Egyptian tombs after getting through these. But got past that.
Secondly, it works, has the depth of focus that is OK, but the frame rate is just too slow to get a good sense of the center of rotation. So another idea down the drain. Apparently a spy doesn't move all that fast.
First, the instructions are absurd. I'm ready to go decode Egyptian tombs after getting through these. But got past that.
Secondly, it works, has the depth of focus that is OK, but the frame rate is just too slow to get a good sense of the center of rotation. So another idea down the drain. Apparently a spy doesn't move all that fast.
- Joined
- Jul 29, 2014
- Messages
- 2,848
I needed to bend a 1/4” thin wall aluminum tube to a 1/2” centerline radius. Yes, I could buy a tubing bender with dies, etc, but all this equipment is sitting around waiting for these moments. And I had barely ever used my $240 dividing head, and never the tailstock that came with it. I set them both up on the mill and used the dividing head just to smoothly rotate a bar while I fed a ball end mill into it, made two spools and parted them on the lathe, drilling a 3/8” hole in each.
Then with a scrap of aluminum bar, drilled a 3/8” pivot hole, and 3/4” away, drilled and tapped a 3/8-16 thread. One of the spools slipped over a 3/8” bolt held in a vise, the other spool went over a similar bolt screwed into the bar. The bar rotates around the pivot point, and by holding one end of the tube stationary, you rotate the bar and wrap the tube around the pivot roller while the outrigger roller keeps the tube from collapsing.
Surprisingly, it worked exactly as intended.
Or, I could have bought an $8 bender. I think I made the right decision.
Then with a scrap of aluminum bar, drilled a 3/8” pivot hole, and 3/4” away, drilled and tapped a 3/8-16 thread. One of the spools slipped over a 3/8” bolt held in a vise, the other spool went over a similar bolt screwed into the bar. The bar rotates around the pivot point, and by holding one end of the tube stationary, you rotate the bar and wrap the tube around the pivot roller while the outrigger roller keeps the tube from collapsing.
Surprisingly, it worked exactly as intended.
Or, I could have bought an $8 bender. I think I made the right decision.
- Joined
- Nov 24, 2014
- Messages
- 3,704
@Winegrower
Congratulations on your bending tooling and success.
May I recommend, for the next time, filling the tube with a low temperature melting alloy (Cerrobend) which will maintain the roundness and full flow of the tube. Wear your safety glasses when handling the heated alloy.
Congratulations on your bending tooling and success.
May I recommend, for the next time, filling the tube with a low temperature melting alloy (Cerrobend) which will maintain the roundness and full flow of the tube. Wear your safety glasses when handling the heated alloy.
- Joined
- Jan 2, 2014
- Messages
- 9,540
.........but @Winegrower 's bends look perfect from here!
There was no kinking or collapse of the tube.
I guess it's all down to this:
There is extra pain, expense and time of buying new materials, melting, filling, cooling, and then re-melting to remove.
Sometimes it may be required, other times not.
It really depends on the project.
Thanks,
-brino
Last edited:
- Joined
- Jul 29, 2014
- Messages
- 2,848
The groove is 0.125 deep, so when the rollers are in position it’s basically a nice round circle that’s formed, exactly the diameter of the tube. I intentionally placed the rollers just slightly further apart than exactly 0.75 so the tube could get started easier. Yep, occasionally I can plan ahead.
Brino is right, the tube really did turn out great, and I’m also happy to get extropics reference to Cerrobend, for possible future reference.
Brino is right, the tube really did turn out great, and I’m also happy to get extropics reference to Cerrobend, for possible future reference.
- Joined
- Nov 24, 2014
- Messages
- 3,704
It works very well in difficult to bend circumstances such as tight radiuses. It is not a universal guarantee to bend any dimension of any material.
If the tube is split while using Cerrobend, I suggest it would certainly kink if not filled with Cerrobend.
The trickiest part of using Cerrobend is getting it into very small diameter tubes. I have filled a Pyrex tube (vertical) with Cerrobend and immersed the workpiece to fill it. Then plug the top end of the workpiece and extract it. It is much simpler if the workpiece is large enough to pour the Cerrobend into while concurrently allowing the displaced air to vent. Low temperature alloys are also used to support/backup features of a machined part too thin to withstand tool pressure without deformation.
Take extreme care and wear full coverage PPE if experimenting with molten Cerrobend. You don't want to be splashed with 117°+ F molten metal.
