Carbon Fiber blank, no Brass tube possible?

[chartle]

I have a crazy idea of making a carbon fiber slim line. I want this to be a true slim line aka slim, not fat. There is very little meat once you turn down to the bushings and afraid I'll start to cut into the CF.

So here is my crazy thought, skip the brass tube. Problem is what to use for a mandrel and how to release the CF tube when set?

I've read a few docs on how to it but I can't just use a regular 7mm mandrel since I need some sort of barrier between the CF and the mandrel and this extra plastic will add extra interior diameter.

 

[Skie_M]

If you have a collet chuck capable of holding a 1/4 inch rod, it should suffice... You can cast your carbon fiber right on the rod and then turn it while still on that rod. The issue will come up, however .... how are you going to attach your pen parts?

The brass tube you want to omit is the ideal method of attachment, as it deforms slightly to profide a good friction fit around the parts that are pressed in. The carbon fiber tube you will end up with will NOT withstand the pressure, and you will have cracks.

It may be possible to just custom cast some carbon fiber tubes that are just carbon fiber directly on the brass tube with very little resin around them, just big enough to be able to turn them right down to slimline 7mm bushings or perhaps a little thinner, but I thought that the carbon fiber tube offerings were already made this way...

Have you cut into the carbon if you go just past the bushings? Is it not possible to "repair" such damage by application of CA to seal it back up again?

 

[chartle]

1. If you have a collet chuck capable of holding a 1/4 inch rod, it should suffice... You can cast your carbon fiber right on the rod and then turn it while still on that rod. The issue will come up, however .... how are you going to attach your pen parts?

2. The brass tube you want to omit is the ideal method of attachment, as it deforms slightly to profide a good friction fit around the parts that are pressed in. The carbon fiber tube you will end up with will NOT withstand the pressure, and you will have cracks.

3. It may be possible to just custom cast some carbon fiber tubes that are just carbon fiber directly on the brass tube with very little resin around them, just big enough to be able to turn them right down to slimline 7mm bushings or perhaps a little thinner, but I thought that the carbon fiber tube offerings were already made this way...

4. Have you cut into the carbon if you go just past the bushings? Is it not possible to "repair" such damage by application of CA to seal it back up again?

1. I think the issue is how to remove the blank from the rod.

2. If it fit tightly but not as tight as in a tube I could glue the parts in.

3. Thats my plan for some thicker blanks.

4. I'll let you know once I get the CF and get some castings done.

 

[Sylvanite]

I once made a carbon fiber siimline pen by:

1. Painting the tubes black (so that no brass would show through),
2. Gluing carbon fiber sleeve to the tubes with thin CA glue,
3. Trimming the excess carbon off (with proper safety precautions, because it's hazardous to breathe),
4. Building up CA glue proud of slimline bushing diameter,
5. Turning back down to size,
6. Sanding/buffing the blanks and assembling the pen.

I didn't cut into the carbon fiber when turning, and the pen came out just fine. I expect that if you started with a cast carbon fiber blank on a 7mm tube, you'd be fine turning it down to slimline diameter as well.

I hope that helps,
Eric

 

[chartle]

Well I figured out what to use as a properly sized mandrel, a knitting needle, they come in various thickness in half mm increments and are super straight. Much better than I could get in a hardware store.

I'll try the technique above first, don't even need to cast it.

 

[Kenny Durrant]

I've cast several snakes and Carbon Fiber 7mm blanks. I've never had problems on the ends cutting through and I've always left a swell in the center of the tube for two reasons. 1st I'm scared that if I'm not straight across the bushing I'll dip into the fiber and 2nd I do like the somewhat hour glass figure of the pen. I think Eric has a good idea it's up to you if you want to use ca glue or resin to build up the blank.

 

[skiprat]

I reckon even if you use the tubes you should be ok. I think you will have far more issues if you try and skip the tubes. What will the mech be pressed into?
Let us know what happens....

 

[Skie_M]

1. If you have a collet chuck capable of holding a 1/4 inch rod, it should suffice... You can cast your carbon fiber right on the rod and then turn it while still on that rod. The issue will come up, however .... how are you going to attach your pen parts?

2. The brass tube you want to omit is the ideal method of attachment, as it deforms slightly to profide a good friction fit around the parts that are pressed in. The carbon fiber tube you will end up with will NOT withstand the pressure, and you will have cracks.

3. It may be possible to just custom cast some carbon fiber tubes that are just carbon fiber directly on the brass tube with very little resin around them, just big enough to be able to turn them right down to slimline 7mm bushings or perhaps a little thinner, but I thought that the carbon fiber tube offerings were already made this way...

4. Have you cut into the carbon if you go just past the bushings? Is it not possible to "repair" such damage by application of CA to seal it back up again?

1. I think the issue is how to remove the blank from the rod.

2. If it fit tightly but not as tight as in a tube I could glue the parts in.

3. Thats my plan for some thicker blanks.

4. I'll let you know once I get the CF and get some castings done.

1. Wax the rod liberally .... so the CA or resin used doesn't stick to it.

2. I could see gluing the parts in, but if enough pressure is applied laterally (from the sides), would the pen barrel hold up without snapping?

3. When the clear resin that the carbon fiber tubes are in gets down fairly close to the bushings they are designed for, you get a lensing effect that magnifies the contents, making them appear much closer to the surface than it really is.

Get a small flat piece of glass or backer board (sand edges of glass for safety), and glue some 220 grit paper to it. Hold it between the bushings as level as you can, or if you don't mind possibly ruining a set of 7mm bushings, just hold them across the bushings and sand till you hit both bushings, without rocking back and forth, you should end up with a nice and straight barrel with no tearout of carbon fiber.

4. Seems that from what other people say, such repair is possible if you don't cut all the way through. But to avoid seeing the brass tube underneath, painting it black (or whatever color you are using for carbon fiber) would be a good idea.

 

[79spitfire]

Carbon fiber is commonly used for items such as bicycle handlebars, with no interior tube. I think your concept is solid. You WILL likely end up gluing the hardware to the finished tubing. I would begin by researching how carbon fiber rigid tubing is made.

 

[jttheclockman]

I have a crazy idea of making a carbon fiber slim line. I want this to be a true slim line aka slim, not fat. There is very little meat once you turn down to the bushings and afraid I'll start to cut into the CF.

So here is my crazy thought, skip the brass tube. Problem is what to use for a mandrel and how to release the CF tube when set?

I've read a few docs on how to it but I can't just use a regular 7mm mandrel since I need some sort of barrier between the CF and the mandrel and this extra plastic will add extra interior diameter.

They sell carbon fiber tubes or solid rods which you can drill out to size. You can buy them on ebay

 

[Skie_M]

I have a crazy idea of making a carbon fiber slim line. I want this to be a true slim line aka slim, not fat. There is very little meat once you turn down to the bushings and afraid I'll start to cut into the CF.

So here is my crazy thought, skip the brass tube. Problem is what to use for a mandrel and how to release the CF tube when set?

I've read a few docs on how to it but I can't just use a regular 7mm mandrel since I need some sort of barrier between the CF and the mandrel and this extra plastic will add extra interior diameter.

They sell carbon fiber tubes or solid rods which you can drill out to size. You can buy them on ebay

Now, a solid fiber tube or rod sounds like a plan!

 

[dyaus75]

carbon fiber

If you know about fishing rods, many rods are built from carbon fiber.

rough process is below.

1. wrap the mandrel with carbon fiber

2. applying kind of resin

3. toasting in the oven.

4. remove mandrel

5. get carbon fiber tube for fishing rods.

Ref: https://youtu.be/2mH0VIsUt9c

- If you find suitable resin and curing temperature, you can build carbon fiber tube without brass tube.

 

[Skie_M]

If you know about fishing rods, many rods are built from carbon fiber.

rough process is below.

1. wrap the mandrel with carbon fiber

2. applying kind of resin

3. toasting in the oven.

4. remove mandrel

5. get carbon fiber tube for fishing rods.

Ref: https://youtu.be/2mH0VIsUt9c

- If you find suitable resin and curing temperature, you can build carbon fiber tube without brass tube.

This may work, yes, but as I recall, you have to apply the carbon fiber strips in a SPIRAL on the mandrel in order to avoid having it split down it's length.

Just for extra strength, I would wrap clockwise one layer and then counterclockwise for a second layer, and sandwich it all with a generous layer of PR or CA. This might hold up ok for lateral stresses.

 

[Sylvanite]

This may work, yes, but as I recall, you have to apply the carbon fiber strips in a SPIRAL on the mandrel in order to avoid having it split down it's length.

Just for extra strength, I would wrap clockwise one layer and then counterclockwise for a second layer, and sandwich it all with a generous layer of PR or CA.

Most of us use biaxial carbon fiber sleeve (which is woven in tube form) rather than flat carbon cloth. No spiraling necessary.

Also, if you aren't going to use a brass tube for support, you'll be better off with epoxy resin (such as West System 105 with 207 hardener) and use multiple layers of carbon fiber. Epoxy is much stronger than PR or CA. I recently made some short poles (for waving flags) from carbon fiber. I used thin wall plastic tube for the forms and laid up a single layer of carbon fiber sleeve using vinylester (which is stronger than polyester) resin. That worked, but whenever I show one to somebody, that person inevitably says "Ooh, carbon fiber - how strong is it?" and immediately proceeds to bend the pole until it breaks. I've repaired them with CA, but have to warn people that these are meant for flags - not jousting.

Regards,
Eric

 

[chartle]

If you know about fishing rods, many rods are built from carbon fiber.

rough process is below.

1. wrap the mandrel with carbon fiber

2. applying kind of resin

3. toasting in the oven.

4. remove mandrel

5. get carbon fiber tube for fishing rods.

Ref: https://youtu.be/2mH0VIsUt9c

- If you find suitable resin and curing temperature, you can build carbon fiber tube without brass tube.

I would assume regular 5 to 15 minute epoxy should work. I think they use heat cured resin because they need a very long working time because of the multiple layers.

Not sure how strong it will be. Those rods are multiple layers. I'll be using sleeving.

We shall see tonight. I found some 5.5 mm knitting needles that I can build up a tad with something that will let me pull it off. I'll be using 5 min epoxy.

 

[chartle]

This may work, yes, but as I recall, you have to apply the carbon fiber strips in a SPIRAL on the mandrel in order to avoid having it split down it's length.

Just for extra strength, I would wrap clockwise one layer and then counterclockwise for a second layer, and sandwich it all with a generous layer of PR or CA.

Most of us use biaxial carbon fiber sleeve (which is woven in tube form) rather than flat carbon cloth. No spiraling necessary.

Also, if you aren't going to use a brass tube for support, you'll be better off with epoxy resin (such as West System 105 with 207 hardener) and use multiple layers of carbon fiber. Epoxy is much stronger than PR or CA. I recently made some short poles (for waving flags) from carbon fiber. I used thin wall plastic tube for the forms and laid up a single layer of carbon fiber sleeve using vinylester (which is stronger than polyester) resin. That worked, but whenever I show one to somebody, that person inevitably says "Ooh, carbon fiber - how strong is it?" and immediately proceeds to bend the pole until it breaks. I've repaired them with CA, but have to warn people that these are meant for flags - not jousting.

Regards,
Eric

Yea using the correct West system epoxy would be best but not for me just fooling around with carbon fiber. I'm just going to use the Harbor Freight stuff I already have. If I need more working time Hobby Lobby has some 30 minute stuff.

I wish I would have also ordered this heat shrink tubing they have. May have made it easier to get a nice smooth blank since for at least the slimline I won't be casting it.

 

[Sylvanite]

I'm just going to use the Harbor Freight stuff I already have. If I need more working time Hobby Lobby has some 30 minute stuff.

I wish I would have also ordered this heat shrink tubing they have. May have made it easier to get a nice smooth blank since for at least the slimline I won't be casting it.

Note that 5 and 30 minute epoxy will yellow over time. West 105/207 stays clear. With plain black carbon fiber, that may not be particularly noticeable, though.

I've tried the shrink tubing, and although it generally works, the process is not as simple as it sounds. The treated tubing is also quite expensive - it costs more than the carbon fiber sleeve. I've also wrapped carbon tube with clear packing tape sticky-side out. It's messy, and some surface cleanup is necessary afterwards, but it works (and it's cheap). The preferred way to do carbon fiber layup is vacuum bagging, but I don't have the setup for that.

Regards,
Eric

 

[chartle]

Note that 5 and 30 minute epoxy will yellow over time. West 105/207 stays clear. With plain black carbon fiber, that may not be particularly noticeable, though.

I've tried the shrink tubing, and although it generally works, the process is not as simple as it sounds. The treated tubing is also quite expensive - it costs more than the carbon fiber sleeve. I've also wrapped carbon tube with clear packing tape sticky-side out. It's messy, and some surface cleanup is necessary afterwards, but it works (and it's cheap). The preferred way to do carbon fiber layup is vacuum bagging, but I don't have the setup for that.

Regards,
Eric

I was thinking the shrink tubing would yield a better surface. I had thought of some sort of tape but was thinking it would leave spiral marks. I've seen videos on how to make these blanks so I may just not worry about it and keep it simple.

Box just came in so we shall see.

 

[chartle]

Ok I applied some car wax to my mandrel and then wrapped it in Teflon pipe sealing tape.

I've done this before for other applications and here is what I got. it's pretty strong but seems a tad soft. Needs more coats of either expoy or CA.

 

[chartle]

Update, it's a little stiffer after letting the 5 min epoxy cure overnight so one more coat of epoxy before switching to CA should just about do it.

One issue I already see is that I can't get the tolerances that kits need to work correctly.

The inside diameter is just a few thousandths too big. If it's an issue with the pressed in hardware I can just add a little glue but it won't grab the outside of the transmission. I'll probably have to add a bit of thin tape to get it to grab.

One note about working with Carbon Fiber sleeving. I thought .25 in would be prefect for a 7mm approx .25 in mandrel. .25 must be the outside diameter. While I could slip it on it was very tight. The .5 in worked much better "slimming" down to that size.

One tip if using a pen mandrel, add a bushing to the mandrel before you start. Pulling on the bushing is the only way you are going to get the tube off in one piece. Now that I think back to all the "How it's Made" episodes where they made CF tubes for fishing poles or pole vault poles it seems that's how the mandrel was extracted. By pushing the tube off. If you pull it off there is a good chance that you will crush it.

 

[chartle]

Ok came home and before dinner added another coat of 5 min epoxy. After at least an hour I started to wet sand the ridges down. The second coat of epoxy pretty much peeled off so I removed it. Not sure why epoxy didn't stick.

So I decided to build up CA. After 10 or so coats of medium I switched to some gel I never use and after 3 coats it was thick enough so I sanded and polished the two pieces and they came out ok. So decided to to use a copper kit I had. Kind of a riff one of the first metals used with the "latest greatest" material.

Well I had to glue the pieces in and had somehow had CA all over the blank. Put the blank back on the lathe and somehow glued it to the mandrel. I had to turn it off so all I have is one section.

Not giving up. I now know that two layers of CF will fill out the kit nicely but pretty sure I could use the brass tube..

Oh and the one piece I have is as strong as a pen with a tube.

 

[jttheclockman]

Ok came home and before dinner added another coat of 5 min epoxy. After at least an hour I started to wet sand the ridges down. The second coat of epoxy pretty much peeled off so I removed it. Not sure why epoxy didn't stick.

So I decided to build up CA. After 10 or so coats of medium I switched to some gel I never use and after 3 coats it was thick enough so I sanded and polished the two pieces and they came out ok. So decided to to use a copper kit I had. Kind of a riff one of the first metals used with the "latest greatest" material.

Well I had to glue the pieces in and had somehow had CA all over the blank. Put the blank back on the lathe and somehow glued it to the mandrel. I had to turn it off so all I have is one section.

Not giving up. I now know that two layers of CF will fill out the kit nicely but pretty sure I could use the brass tube..

Oh and the one piece I have is as strong as a pen with a tube.

Just for my curious mind, why go through this trouble??? CF sleeve over a tube. You will not see what the pen is made from when assembled. Maybe I am missing something here. I will give you points for trying something new. Good luck.

 

[chartle]

Ok came home and before dinner added another coat of 5 min epoxy. After at least an hour I started to wet sand the ridges down. The second coat of epoxy pretty much peeled off so I removed it. Not sure why epoxy didn't stick.

So I decided to build up CA. After 10 or so coats of medium I switched to some gel I never use and after 3 coats it was thick enough so I sanded and polished the two pieces and they came out ok. So decided to to use a copper kit I had. Kind of a riff one of the first metals used with the "latest greatest" material.

Well I had to glue the pieces in and had somehow had CA all over the blank. Put the blank back on the lathe and somehow glued it to the mandrel. I had to turn it off so all I have is one section.

Not giving up. I now know that two layers of CF will fill out the kit nicely but pretty sure I could use the brass tube..

Oh and the one piece I have is as strong as a pen with a tube.

Just for my curious mind, why go through this trouble??? CF sleeve over a tube. You will not see what the pen is made from when assembled. Maybe I am missing something here. I will give you points for trying something new. Good luck.

If you go back to my first post I was afraid that tube plus a sleeve would be too thick for a true slimline.

 

[MartinPens]

I have been meaning to go down to this place and check these out. Interested in seeing the sizes and asking about cutting.
http://www.acpsales.com/Carbon-Tubes.html

 

[jttheclockman]

Ok came home and before dinner added another coat of 5 min epoxy. After at least an hour I started to wet sand the ridges down. The second coat of epoxy pretty much peeled off so I removed it. Not sure why epoxy didn't stick.

So I decided to build up CA. After 10 or so coats of medium I switched to some gel I never use and after 3 coats it was thick enough so I sanded and polished the two pieces and they came out ok. So decided to to use a copper kit I had. Kind of a riff one of the first metals used with the "latest greatest" material.

Well I had to glue the pieces in and had somehow had CA all over the blank. Put the blank back on the lathe and somehow glued it to the mandrel. I had to turn it off so all I have is one section.

Not giving up. I now know that two layers of CF will fill out the kit nicely but pretty sure I could use the brass tube..

Oh and the one piece I have is as strong as a pen with a tube.

Just for my curious mind, why go through this trouble??? CF sleeve over a tube. You will not see what the pen is made from when assembled. Maybe I am missing something here. I will give you points for trying something new. Good luck.

If you go back to my first post I was afraid that tube plus a sleeve would be too thick for a true slimline.

Well I just do not see it. Thickness of a tube is so minimal. You still have to make the blank thick enough to support the components when you glue them in or it will crack when dropped.

Carbon fiber slimline

 

[Badfrog]

my first pen ever was a bolt action kit that my father gave me... at the time I did not have a lathe. Another hobby of mine is designing and building custom multi rotors (yes, the dreaded "drones"!). I had some 10mm carbon fiber tube stock used for multirotor arms that turned out to be the perfect diameter for the pen kit. I cut it to length, trimmed the ends on the sander (careful with CF, the dust is not good to breath!) and put it together - although NOTHING was turned OR cast, it is still one of my favorite pens!
I have not seen (although I have not looked either) CF tube in 7mm. again, this takes away the casting and turning aspect, but might end up with a cool pen!

 

[chartle]

After a few CF failures, I moved to another black a wanted to try to make, marble and other stones like turquoise using polymer clay.