Delrin bushing

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SteveM
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Delrin bushing

Post by SteveM »

We have tower trailers for ham radio antennas.

They have a 2-3/8" hole at the top and we need to put a 2" OD antenna mast thru it, so we need a bushing.
Trailer.jpg
I was thinking Delrin AF would be perfect, then I saw the price. Most of the piece would be machined away, and buying tube would save money, but I can't find tube that large.

These are not going to be seeing any high rotational speeds, and in the course of the day, we might do the equivalent of 10-20 revolutions.

With a 2" mast, the wall thickness will be about 3/16".

The bushing would have horizontal side loads but no tilting loads, as the mast would be supported by the rotor, which will sit maybe two feet down from the bushing.

I've found people selling plain delrin drops on ebay for cheap enough.

Would plain delrin work for such an application?

Would it be OK for that wall thickness?

Or is there a better material to use?

Steve
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Bill Shields
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Re: Delrin bushing

Post by Bill Shields »

If it is contained it will be ok ..but I would worry about I coming loose.

All things considered...what is wrong with brass or bronze?

Nylatron would be good.
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oldbrock
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Re: Delrin bushing

Post by oldbrock »

I have actually used wood for that kind of application. Use maybe birch and after machining soak it in linseed oil. make a shoulder bushing so it doesn't fall out.
Last edited by oldbrock on Sat Dec 17, 2022 5:02 pm, edited 1 time in total.
Difficult done right away, impossible takes time.
oldbrock
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Re: Delrin bushing

Post by oldbrock »

Probably free material. use your firewood pile
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Bill Shields
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Re: Delrin bushing

Post by Bill Shields »

Arboga?
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Russ Hanscom
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Re: Delrin bushing

Post by Russ Hanscom »

What about 2" PVC pipe, which is almost exactly the size you need at 2 3/8" od. Use sch 40 or sch 80 to get enough wall thickness and then a bit of lathe work to bore to size.
SteveM
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Re: Delrin bushing

Post by SteveM »

Bill Shields wrote: Sat Dec 17, 2022 12:30 pm If it is contained it will be ok ..but I would worry about I coming loose.
All things considered...what is wrong with brass or bronze?
Nylatron would be good.
It will have a shoulder on it do it won't drop.
It might be easier to find brass pipe close to the right size.
McMaster has MDS-filled nylon in tubes that are pretty close to size.
Russ Hanscom wrote: Sat Dec 17, 2022 4:57 pm What about 2" PVC pipe, which is almost exactly the size you need at 2 3/8" od. Use sch 40 or sch 80 to get enough wall thickness and then a bit of lathe work to bore to size.
With PVC, I could glue on pieces to make a shoulder on each end so it doesn't come out.
Might be good to cut an oil groove in it for lubrication.

Steve
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rmac
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Re: Delrin bushing

Post by rmac »

If you've got lots more time than money:
  1. Find a tin can of appropriate size to use as a mold.
  2. Send your wife to the movies for the afternoon so she won't know how you're about to abuse the kitchen oven until after the fact.
  3. Cast yourself a slug of HDPE.
  4. Scrape up the blobs of plastic that somehow wound up melted and stuck to the bottom of the oven. If you're good at multitasking, you can also use this time to think up a plausible explanation for why the house smells funny. Otherwise, just concentrate on cleaning the oven and say the dog farted.
  5. By this time you will have been banished to your shop. That's okay, though, because you need to machine away everything (including the tin can) from your HDPE slug that doesn't look like the outside of a bushing.
  6. Still banished to the shop? Thought so. Go ahead and make a set of soft jaws so you can hold the part in the next step without deforming it.
  7. Bore out the inside of the bushing.
Oh, wait ... you said "tower trailers". For "ham radio antennas". As in more than one. This could take a while. :D

-- Russell Mac
oldbrock
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Re: Delrin bushing

Post by oldbrock »

I still say use wood and soak in oil after machining. Way cheaper than anything else and will last as long as plastic.
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Bill Shields
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Re: Delrin bushing

Post by Bill Shields »

Which is what we use in our combines ..wood bearings.

Used to be made by a company IIRC called Arboga (or similar)
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Russ Hanscom
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Re: Delrin bushing

Post by Russ Hanscom »

With PVC, cut a ring, split it, Glue the split ring over the bearing tube following the glue instructions carefully, and put a worm gear hose clamp on it until the glue has fully set. Works quite well.
Jon W
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Re: Delrin bushing

Post by Jon W »

You might want to avoid PVC if these are going to spend their lives outside, as its surface degrades and gets brittle/looses its impact resistance with extended exposure to UV/sunlight.

If you go with a dissimilar metal, beware of galvanic action/degradation if these will see rain or snow.
Jon W
Somewhere North of Boston
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