Anyone here an expert on machining phenolic?

astjp2

astjp2

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I am going to make some phenolic pulleys, I have a local tool grinder make me a tool to turn the groove, I am going to use a HSS parting tool, what angles should be on the tool for rake, etc. ? I also need to bore a precise hole and broach a square hole, Can I use a chucking reamer and a standard broach? I dont think that drill bit will be precise enough. I have about a +- .002 tolerance on the hole. I will post pics when I get a chance. Tim
 
When I ran phenolic back in the day, we used standard HSS end mills and mill tools. For the lathe, my inclination is to use zero rake tools for plastic and soft materials. Glass-reinforced phenolic reacts differently, and dulls tools quick. Using a chucking reamer is good to go, broach should be just fine too.

Truthfully, I think you'll figure out feeds, speeds, and tool end radius in about 5 minutes after you start working with the material. You have wide margins for the work envelope and will quickly find what's best. When in doubt, try a general purpose tool and go to work.
 
I have machined lots of linen reinforced phenolic, you can use HSS tools on it, but in the case of drills and reamers, you are likely ging to see tool binding and tight fits on the holes. When broaching, the hole should be backed up with another thickness of material to avoid breakout on the opposite side. I agree that zero rake tools are appropriate, but a few degrees of rake will not hurt either. I see that the specs call out linen reinforced, so it should not be a big problem.
 
Period correct restoration on your airplane?

If not why not change to delrin or another modern material? Provided it will pass inspection of course....

Cheers,

John
 
What’s a modern equivalent that is good with temps around ~300 °F? Ideally a good thermal insulator.
 
matthewsx said:
Period correct restoration on your airplane?

If not why not change to delrin or another modern material? Provided it will pass inspection of course....

Cheers,

John
Click to expand...
I am going to make a few because people requested me to. I have a 1941 airplane, I work on several others and I make a few parts when owners need them. It gives me an excuse to get my lathe running and a few small easy projects to learn on. This pulley is just complex enough to get me started. I still need to get my DRO installed and do some lubing and cleaning of the lathe before I really make anything. Small projects that have a purpose will get me experience in using my lathe, normally I just fix them.

Changing material is not allowed without testing and I can get the original material so if I am duplicating original, no special certifications. I am an inspector and a mechanic so I have to follow the rules to keep my certificaitons. Tim
 
astjp2 said:
I am going to make a few because people requested me to. I have a 1941 airplane, I work on several others and I make a few parts when owners need them. It gives me an excuse to get my lathe running and a few small easy projects to learn on. This pulley is just complex enough to get me started. I still need to get my DRO installed and do some lubing and cleaning of the lathe before I really make anything. Small projects that have a purpose will get me experience in using my lathe, normally I just fix them.

Changing material is not allowed without testing and I can get the original material so if I am duplicating original, no special certifications. I am an inspector and a mechanic so I have to follow the rules to keep my certificaitons. Tim
Click to expand...

Sounds like the right material for your project then.

My dad was a pilot and homebuilder but I am neither, would love to see a picture of the aircraft in question.

Cheers,

John
 
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