Tru-stone keeps cracking

[dfolk]

My last few attempts at pressing together a tru-stone pen resulted in a cracked blank when I pressed in the last piece on the cap. Any ideas how I can stop this from happening?

On a the good side I am getting proficient at disassembly.

Thanks
Dennis

 

[BSea]

I had the same issue on some scalloped pens not long ago. I ended up putting the fitting in my collet check & filing down the fitting to the brass where it would just slide in. then I used locktite to seal in the the cap would be a bit more of a challenge, but you should be able to do it. You might have to make a piece out of scrap depending on what kind of cap it is.

Or if you have a punch set. Just use the largest punch that fits almost tight inside the cap, then use some tape to give it a snug fit. And if you don't have a collet chuck, you could use a drill chuck in the headstock.

 

[1080Wayne]

Make sure no glue in tube , chamfer tube end , ream out tube a bit oversize , then epoxy the piece in

 

[Sylvanite]

Another option is to press in the brass parts (such as the finial) and knock them out before gluing in the tube. That way, the tube is pre-expanded and will have less tendency to crack the blank later. When you install the fittings again, add a drop of loctite and be very careful to insert them straight.

Regards,
Eric

 

[randyrls]

I would agree with Wayne; Make CERTAIN there is not the slightest bit of glue in the tube. The pen mill isn't sufficient for this task.

With the bare brass tube, select a transfer punch that will just fit into the tube. Put it into the brass tube and twist gently sideways while spinning the tube. Do this until the fitting just slips into the tube. Make the pen as normal. You may have to use a slightly larger drill bit. When the pen is ready for assembly, put a drop of epoxy, CA, or Locktite into the tube and slide the fitting into the tube with a twisting motion. IMPORTANT; the drop of glue must go into the tube, not on the fitting. If you put the glue on the fitting it will squeeze out onto the fitting. Don't ask!

 

[Boz]

I like the idea of preassembling the pen then knocking it apart and glueing the tubes into the blanks. You still have to be absolutely sure thee is no glue on the inside of the tube. I prefer using a drop or two of Locktite over CA. CA is a mess to work with and gets everywhere it is not supposed to be. I have been using Locktite red to secure bearings in engines for years.

 

[Ted iin Michigan]

Agree with many of the comments above, but I'm not a big fan of gluing the components into the tube. Not that I haven't done it - I have. After making completely sure there's no adhesive in the tube, lately I've been wrapping a piece of 220 around a transfer punch and "reaming" the tube just a hair. Then I've been putting some light oil (air tool oil) on a Q tip and swabbing the tube. Seems to work well.
Additional note - TAKE IT EASY! Definately go SLOW when pressing. Most of the materials (Tru-stone included) have some resiliency. But a shock can (will) cause a failure.

 

[Holz Mechaniker]

Make sure no glue in tube , chamfer tube end , ream out tube a bit oversize , then epoxy the piece in

I agree with Wayne too

 

[mikespenturningz]

Make sure that the end of the blank is truly square and the brass is shiny all the way around. I have had trouble with blanks breaking only when I mess up on my end with squaring the blank. You end up with a high spot and that gets a tremendous amount of pressure on it and bang you have a crack. I have had thi happen on acrylic blanks.

 

[BeSquare]

I also find a burnishing tool from the plumbing section of the hardware store helps a lot. Gives a small angle to the end of the brass and helps transition the pen hardware to the inside diameter of the tube.

 

[Katsin]

I did my first tru-stone the other week... white with gold webbing. It went well land I immediately dove into an attempt of black with gold webbing.

I am very frustrated with the black material at this point as I have cracked two lower barrels and two upper barrels at the point of assembly. I was careful to ream barrel edges and use acetone to clean out any glue inside the tubes.

Is sanding much preferred to pen mills for cleaning up the ends of tru-stone? I worry that pen mill I have (no sander as an option) is leaving poor edges that I can't see with the unaided eye which is encouraging cracking.

Also, when it comes to glue up, I have noticed from the cracked blanks that glue up on the brass tubes is not a nice even coating. The brass tubes seem to push the 15 minute epoxy that i use completely out of the tube. Any advice on a nice even glue-up over the tube?

 

[dfolk]

I just made another attempt, and went one for two. I pressed in the pieces and knocked them out before gluing the tubes and I sanded the inside of the tubes before assembly. The one that cracked may still have been a little tight so on the second one I sanded the pieces a little before I pressed them in and it worked out OK. I may have over turned the first tube just a bit as well. Like Katsen I noticed there were some gaps between the tube and blank (very small) where the epoxy didn't coat. On the second attempt I filled the gap with a little CA. I like the looks of tru-stone but it has been a bit difficult to figure out.

I wonder if tru-stone is that touchy will the pen crack the first time someone drops their pen.

Dennis

 

[BSea]

I wonder if tru-stone is that touchy will the pen crack the first time someone drops their pen.

Dennis

It might. Tru-stone (as you know) is pretty brittle. But so is PR. And they get dropped all the time. I think the tube will help prevent it from cracking, but it's still possible.

 

[jfoh]

Not always the tubes fault. I had a few pen kits that measured a few thousand's over size. Do not know if they had extra plating or just were made slightly oversize. When in doubt measure several different kits to see if they vary.

True stone is not very forgiving. If the part being pressed in is not exactly in line or canted slightly they will crack. If glue remains in the tube it will crack. If you drop it onto a hard surface you hope it does not crack. Still worth all the problems as it is a very nice finished pen, if it does not crack.

 

[PenMan1]

I always drill black Tru-Stone with soapy water and the cool the blank after every 1/4 inch of drilling with a cold water and paper towel compress.

THEN I NEVER use a pen mill on Tru-Stone, but rather use a disc sanding jig or skew tip to square the tube ends. My THEORY is that pen mills cause chips, no matter how carefully you use them. THEN when applying the pressure of inserting hardware causes these microscopic chips to develop into stress cracks. To check out this theory for yourself, use a pen mill, THEN examine the ends with a 17X jeweler's loupe!

Finally, before pressing, I use a bullet chamfer tool that I bought long ago from Arizona Silohuette. This is perhaps one of the most useful tool in the shop. When I press, I apply 1 drop of Loctite to the hardware being pressed. I do this for two reasons. First, the thread sealant is "slick" and acts as a lubricant as the parts are friction fit. Secondly, as the Loctite dries, it makes an excellent bond between the tube and the hardware, yet the parts can still be disassembled, if necessary.

FWIW: I had many, many sticks of black/gold web Tru-Stone in my shop. Many pieces made BEFORE the factory explosion and some made after. In EVERY case, the newer stone was more brittle and more "powdery" when drilled. I can't help but think that the "formula" changed after the explosion.

Respectfully submitted.

 

[Katsin]

THEN I NEVER use a pen mill on Tru-Stone, but rather use a disc sanding jig or skew tip to square the tube ends. My THEORY is that pen mills cause chips, no matter how carefully you use them

Although I don't have a sander myself, I have access to one at a nearby relative's house so I will give that a try on the next attempt. Thank you for the advice.

 

[PenMan1]

The only problem with using a disk sanding jig on black Tru-Stone is that your face looks like Al Jolson when you finish. I HIGHLY RECOMMEND using a least a dusk mask during this process!

 

[Katsin]

The only problem with using a disk sanding jig on black Tru-Stone is that your face looks like Al Jolson when you finish. I HIGHLY RECOMMEND using a least a dusk mask during this process!

Good advice. I've been using a dust mask on everything tru-stone so far but plan on something better like P95 if I turn more of it. Don't want to get Silicosis since it can be fatal.

 

[flyitfast]

I have found using one of these from Harbor Freight on each end of tube before assembly really helps with insertion of parts. Use the pointy reamer and it bevels the end of the tube so parts have easier entry. Eases the shock when part slides in. Well worth the $3.99, especially wihen on sale or with a coupon.

Reamer/Deburring Tool

gordon