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2nd May 2021, 05:41 PM #1
Ham Radio Tower Traveller Pulley Replacements
Hi All
To continue on from the 'Top Pulley Replacements' my mate has asked me to make 6 x Traveller pulley replacements for the carriage that gets wound up & down with the rotator & antenna on it, this is wound down in windy conditions;
IMG_2186-2.jpg
Here is a look at the pulleys;
IMG_2181.JPGIMG_2183.jpgIMG_2182.jpg
He has purchased some Delrin (I think) for me to make these out of;
IMG_2184.jpg
I have ordered another HSS parting tool to hopefully be able to part it off in one go with no hacksawing required, I do on the other hand have a minor issue with how to get the 27mm dia groove into the Delrin.
I am thinking about parting off 6 x biscuits of the delrin then mounting them (1 at a time) in the rotary table on the mill at 90° and using a 27mm dia end-mill while rotating the rotary table to cut the groove.
Does this sound feasible??, if so, where do I get a 27mm end-mill bit??
Cheers All
Peter
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2nd May 2021, 05:53 PM #2Senior Member
- Join Date
- Oct 2009
- Location
- Upwey VIC
- Posts
- 187
A shallow V-groove may be enough.
Delrin is easy to machine with sharp HSS tools on a lathe.
Andrew
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2nd May 2021, 06:14 PM #3
Hi Peter, Guys,
When I made mine, some years ago now ! I turned a form tool from a piece of bar the same diameter as the mast tube. I didn't bother hardening it. It was made from 1/4" plate with a 15 degree back rake and a flat top. I filed one edge off to give me a flat side that I could get into the toolpost and clamp down.
My pulleys were made from 3" diameter Nylon 60 bar, sliced into 30 mm thick chunks and faced off. They were drilled and mounted on a 7/8" inch mandrel and the groove turned. Because of the sizes needed, I used a live centre in the tailstock to support that end of the mandrel, it also helped with the chatter that got worse as the form tool edge wore off. I re-sharpened the form tool a couple of times on a belt sander by sanding the flat top.
Mine ran on 1/2" inch bolts in brass inserts.
Everything has gone now ! I tried to sell the tower and rotator gear but no one was interested, so it all got cut up for scrap. I still have the rotator and the TS700S radio. Unfortunately the kilowatt transmitter crapped its smoothing capacitors, I still have that as well, but its in bits, I couldn't get replacement capacitors at the time.Best Regards:
Baron J.
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2nd May 2021, 06:19 PM #4
To do in the lathe you could tack weld 2 pieces of HSS together and make a form tool, it machines easy with sharp tooling.
You could make a radius turning tool for the lathe either from scratch or using a cheap mill boring head.
You could also do it with a boring head in the mill with the rotary table vertically.
Quick and easy I'd go for the welded HSS.
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2nd May 2021, 07:13 PM #5Most Valued Member
- Join Date
- Nov 2007
- Location
- melbourne australia
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- 3,228
I reckon I would make a form tool as BaronJ or Dave suggested and do it all on the lathe. I would first cut all the grooves in an appropriate length of the Delrin with a live centre for rigidity, then part them off. Then face them to final width and drill or bore the holes as required
Chris
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7th May 2021, 05:00 PM #6Most Valued Member
- Join Date
- Mar 2011
- Location
- Southern Flinders Ranges
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- 1,555
Set it up on the rotary table, and use a boring head or fly cutter (bit harder to set up, but still quite doable) to cut the radius
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7th May 2021, 07:06 PM #7Philomath in training
- Join Date
- Oct 2011
- Location
- Norwood-ish, Adelaide
- Age
- 59
- Posts
- 6,561
I'd follow Andrew's tip and do a V groove. I can't think of anything you really would gain using a shallow form. I'd probably do something like a 60 degree groove so it did not slip off easily, but probably does not matter too much.
Michael
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