Phenolic education: lathe turning and spin forming

[Skillet Maker]

Hi! I'm new here, my name is Peter
I need some help figuring out how to use Phenolic as a spin form for metal spinning.

I have searched far and wide and solid info on what grades of phenolic to use and machining it has been very elusive.

Here's the problem:
I spin the lid for one of my big pans on Eastern Hard Maple. The wood grain from the Maple telegraphs though the spun part. When I hand sand the lid surface (while spinning on the lathe) the grain pattern magically appears, I don't like that. Also, I've had to make little repairs around the perimeter of the form, first with Bondo and then with Maple wedges glued into a "V" cut that removed the damaged area. The V's are only about 3/8" wide. As I used the form with the new wood wedges, I found that the wood around the wedges has been compressed from repeated spinning over time and the new wood, being less dense has been compressed below the plain of the surrounding wood. This leaves a little ripple on the lid at that spot. The lid is a large dome shape so making a replacement form in steel is both time and cost prohibitive. I've tried with smaller lids.

On youtube I have seen video's of people using phenolic as a spin form. Do any of you wise people here have any experience doing this? I think I'll be turning the Phenolic form on a wood lathe, thats the plan anyway. I'll also need to cut threads (8tpi X 1") in it for mounting on the lathe.
I'm interested in learning what grades are best for the application I'm proposing and insight into machining it. From what I have found so far the paper based mechanical or economy grade it the one to use. I have piece of canvas economy grade I'm goin to play with for one of my smaller lids. The piece I'll need for the big lid replacement is 2.5" thick X 13.5" square. I want to be sure I'm getting the right/best stuff because it ain't gona be cheep!
Sorry for such a long winded first post but this problem has been dogging me for a couple a years...

Thank you fro any and all suggestions!

Peter

 

[Scruffy887]

Skillet maker? Are you Peter Pan the skillet maker?
Seriously, that thickness can be just a few pieces laminated together and Bobs your Uncle. Yes, can turn it by hand, get dust extraction, carbide tooling, ability to hone carbide tooling, solid hand skilz. Dust mask too. I do loads of stuff with thick phenolic. You can tap it, thread mill it, etc. Controlled Shop environment will keep it from moving about. Paper based phenolic is a wood based product. The long direction on a sheet is usually the paper grain direction. Yup, grain direction just like wood. It can and will change dimensions with humidity just like wood, but not as much.
I have loads of 1" and all have a finish layer of melamine coated paper. For your needs that would need to be skimmed off to laminate. Laminate a few pieces together with JD weld and go for it.
The canvas and linen type is very strong, but not so flat as the thick paper based stuff.
Could I make a few blanks thread milled for you? Four letter word is "work". Maybe. I have 2 Mazaks reserved and tooled for phenolic fixtures for our own internal use. Maybe no more than 2-3000 pounds of the stuff on hand.

 

[Scruffy887]

Additional info. You are currently forming against maple side/edge grain. You could try forming against end grain. Forms would be a little more complicated to build.

 

[johansen]

What if you spin form an aluminum sheet metal
surface over the top of your wood pattern, then epoxy it to the wood pattern and use it as your master after cleanup and re profiling?

You are right a piece of phenolic that size wont be cheap, but there is another material that might work, you can heat form a sheet of corian over the top of your master, then clean up and reprofile.

 

[Scruffy887]

And WTF is so bad about wood grain on the final product? Seriously, accentuate it. Are you making a hand formed product? Or trying to mimic a Walmart product?

 

[Skillet Maker]

And WTF is so bad about wood grain on the final product? Seriously, accentuate it. Are you making a hand formed product? Or trying to mimic a Walmart product?

Ha! Thats what my wife says.... She likes it!!!

 

[Skillet Maker]

What if you spin form an aluminum sheet metal
surface over the top of your wood pattern, then epoxy it to the wood pattern and use it as your master after cleanup and re profiling?

You are right a piece of phenolic that size wont be cheap, but there is another material that might work, you can heat form a sheet of corian over the top of your master, then clean up and reprofile.

Great ideas! I've thought about skinning it with Steel. I think Aluminum would gall. Tell me more about heating Corian. I used it for countertops years ago...

 

[Skillet Maker]

Skillet maker? Are you Peter Pan the skillet maker?
Seriously, that thickness can be just a few pieces laminated together and Bobs your Uncle. Yes, can turn it by hand, get dust extraction, carbide tooling, ability to hone carbide tooling, solid hand skilz. Dust mask too. I do loads of stuff with thick phenolic. You can tap it, thread mill it, etc. Controlled Shop environment will keep it from moving about. Paper based phenolic is a wood based product. The long direction on a sheet is usually the paper grain direction. Yup, grain direction just like wood. It can and will change dimensions with humidity just like wood, but not as much.
I have loads of 1" and all have a finish layer of melamine coated paper. For your needs that would need to be skimmed off to laminate. Laminate a few pieces together with JD weld and go for it.
The canvas and linen type is very strong, but not so flat as the thick paper based stuff.
Could I make a few blanks thread milled for you? Four letter word is "work". Maybe. I have 2 Mazaks reserved and tooled for phenolic fixtures for our own internal use. Maybe no more than 2-3000 pounds of the stuff on hand.

Scruffy887, are the paper layers placed at 90 degrees to each other like plywood? What grade do you use? I like hearing it can be easily laminated together with JB weld. May I PM you about your material?

 

[Seesecurity]

Why not use a mild steel die?

 

[Skillet Maker]

Why not use a mild steel die?

Thanks for the suggestion- I have made one in 1045 steel for a smaller pan. Making a domed middle with a lip around the outside is a tuff project because it's all done on a metal lathe and then hand ground with a 4" side winder to blend and polish all the facets to form a fare curve. With Phenolic or something like it, I can use hand held wood turning tools. Way easier to get a nice fare curve.

 

[newtonsapple]

And WTF is so bad about wood grain on the final product? Seriously, accentuate it. Are you making a hand formed product? Or trying to mimic a Walmart product?

I am totally on board with the idea of exploring options to accentuate this as a feature. You haven't showed us the grained finished product, so maybe it does not work. It sounds interesting at least. You could do variations on combinations of sanding/finishing with different grits and compliance of the blocks or pads. Foam pad backed sanding will tend to leave a uniform finish despite the grain. A harder block or pad will likely accentuate the grain. You might try mixing the grits with the backing firmness.

I would be interested in what sort of finish a non woven drum lays down on lathe. I think it would form a pretty uniform finish. Then you might try hard blocks or drum with a different grit.

 

[Skillet Maker]

I am totally on board with the idea of exploring options to accentuate this as a feature. You haven't showed us the grained finished product, so maybe it does not work. It sounds interesting at least. You could do variations on combinations of sanding/finishing with different grits and compliance of the blocks or pads. Foam pad backed sanding will tend to leave a uniform finish despite the grain. A harder block or pad will likely accentuate the grain. You might try mixing the grits with the backing firmness.

I will post a picture! I currently use 100 grit followed by 220 grit, all hand held.

 

[L Vanice]

About forty years ago, I bought the entire stock of phenolic from the local GE die shop auction. There was several hundred pounds of it, mostly the canvas type. I have also bought more of it, along with the linen, glass and paper grades, mostly from eBay sellers. Look on eBay before you pay retail. You can join it with epoxy or use screws in tapped holes.

It is great stuff for many purposes, but the dust is not nice. I set a dust collector nozzle next to the work when sanding, milling and turning and use a mask. Drilling, tapping or band sawing is relatively clean work. I use carbide tools for turning and milling. There are inexpensive hand wood turning tools with replaceable carbide inserts that let you use carbide without needing a diamond wheel grinder. The canvas grade has a visible grain (cut threads) that appears when the machined surface is polished on a buffer. Linen is a much finer cloth and the grain is very fine. I have a piece or two of paper grade but don't recall using it. I think it would not be as strong as the cloth grades. I avoid using the glass grade.

By the way, I use hand wood turning tools to turn steel and other metals. It is a great way to machine curves and is a technique that has been in use for hundreds of years. Hardinge was still selling a hand T-rest for their DV-59 lathes in the 1950's and they were available for other makes of metal lathes.

Larry

 

[Skillet Maker]

About forty years ago, I bought the entire stock of phenolic from the local GE die shop auction. There was several hundred pounds of it, mostly the canvas type. I have also bought more of it, along with the linen, glass and paper grades, mostly from eBay sellers. Look on eBay before you pay retail. You can join it with epoxy or use screws in tapped holes.

It is great stuff for many purposes, but the dust is not nice. I set a dust collector nozzle next to the work when sanding, milling and turning and use a mask. Drilling, tapping or band sawing is relatively clean work. I use carbide tools for turning and milling. There are inexpensive hand wood turning tools with replaceable carbide inserts that let you use carbide without needing a diamond wheel grinder. The canvas grade has a visible grain (cut threads) that appears when the machined surface is polished on a buffer. Linen is a much finer cloth and the grain is very fine. I have a piece or two of paper grade but don't recall using it. I think it would not be as strong as the cloth grades. I avoid using the glass grade.

By the way, I use hand wood turning tools to turn steel and other metals. It is a great way to machine curves and is a technique that has been in use for hundreds of years. Hardinge was still selling a hand T-rest for their DV-59 lathes in the 1950's and they were available for other makes of metal lathes.

Larry

Hi Larry,
Where can I learn more about hand turning steel?! THAT is VERY interesting to me! Thanks for the Ebay tip, I will keep my eye out...

 

[memphisjed]

you can have nickel elctroformed over a wood or mdf pattern.
Turning steel to round shape is not that hard. after turning with tools you can rough fair the curves with files- on the lathe. Sand with cushion sanding sticks to polish. Hand turning is old school awesome. Do not fear steel, respect the material and it works with you.
get creative with wood wedges and grain, how many lids have spun patterns in them?

 

[EmGo]

Had a customer who made wheel covers for antique cars - mostly 20" diameter or so, aluminum and stainless spinnings. The forms were all phenolic. Never any grain in them, just the spinning and sanding marks. Seems like phenolic works okay.

LMARR Disk Ltd.

 

[Scruffy887]

Scruffy887, are the paper layers placed at 90 degrees to each other like plywood? What grade do you use? I like hearing it can be easily laminated together with JB weld. May I PM you about your material?

All the same direction. I have counter top grade with a nice flat top surface. 1" plate and some .5" plate. All black core layers and top layer is gray, blue, other patterns as well. Most of it was made by Wilsonart, but have some made by Pioneer Plastics (Pionite) and some black lab grade made by Trespa. Lab grade sheets are 72" x 120", not a US made size. The top finished layer will need to be machined or ground off as most adhesives will not adhere to it reliably. It can be drilled and tapped and screws hold very well into the face. I use Durapoint drills and full withdraw pecking over 3xd. Also done 15xd with flood coolant and full withdraw pecking. It will cook a steel drill bit quickly. I drilled a hole for a 5/16 tap full depth and there was a slight popping sound when the bit retracted (CNC) The chips packed around the flute and the heat expanded gases at the bottom. Yeah, stopped that program at first hole.

 

[Skillet Maker]

So, I've been looking on youtube for hand forming metal on a metal lathe. I've only found a couple so far, this one holds some promise in helping me shape a lid form. Obviously there will be a LOT of trial and error before I get the geometry right. What I have found so far is for small parts forming. I have a 10" diameter form I can practice with...

Here is an interesting link- he is forming a rivet head, maybe 3/8"

 

[Seesecurity]

Thanks for the suggestion- I have made one in 1045 steel for a smaller pan. Making a domed middle with a lip around the outside is a tuff project because it's all done on a metal lathe and then hand ground with a 4" side winder to blend and polish all the facets to form a fare curve. With Phenolic or something like it, I can use hand held wood turning tools. Way easier to get a nice fare curve.

Ah, I see. Makes life easier if you have a cnc lathe.
I make all the dies up to ~350mm dia for our local metal spinning company, some from mild steel, some are hardened if he's doing SS or large enough numbers. When he does really big stuff, in the 1.5m diameter range(think fire pits) he uses laminated marine ply and spins a 1mm steel cover over the top and glues it on, not perfect but it stops the wood from bruising.
Surely given the time it takes to cut up all the pieces of wood/phenolic, laminate them and then form them in to a die it would be economically viable to sub contract the die to shop with a cnc lathe?

 

[EmGo]

Surely given the time it takes to cut up all the pieces of wood/phenolic, laminate them and then form them in to a die it would be economically viable to sub contract the die to shop with a cnc lathe?

Or use a tracer (if you can still find one). Then all you have to do is make the profile shape on a flat piece of aluminum.