Casting Need some help

[jallan]

I have some trouble with casting Liquid Diamond. I follow the instructions and there are always this discolor on the ends only. What am I doing wrong? Any help would be greatly appreciated. Yellow pencil is there to hold the finished blank
Thanks again
Jallan

 

[Terredax]

It appears to me, that it's out of round, and it's cutting into the tube. Do you have a photo from the end?

 

[leehljp]

The discolor is the casting lifting from the tube. Could be a bit wax on the tube, the tube not clean or the way you are squaring the ends of the cast up to the tube.

I used to get that even with CA on oily woods. Pen mills will do that too. Sanding mills are easier to sneak up to the tube. The cast is not sticking too well but that can be overcome. Well, let me ask, is it like that after you cast it, or after you mill/square it to the end of the tube?

If it is happening BEFORE you square it, you are not getting good adhesion; if after, you are using too much pressure or dull cutter to get it squared and the resin is lifting from the tube. Could be heat too. IMO pen mills require pressure to do a decent job. That is why on another post, I was surprised that Woodpecker, a very high end tool company created a pen mill. In the long run they cause as much problems as they solve.

These are my experiences and opinions. Others are welcome.

 

[Cwalker935]

Seems to me that something is causing the separation either during turning or trimming. You might try using a sanding disk when trimming. Do you turn between centers? If so, the separation might be occurring when you tighten the tail stock. If turning with bushings, you could have debris in the tubes if the bushings aren't sliding in easily. Forcing them in could cause the separation. I have similar issues with PR and it's very frustrating.

 

[jallan]

The discolor is the casting lifting from the tube. Could be a bit wax on the tube, the tube not clean or the way you are squaring the ends of the cast up to the tube.

I used to get that even with CA on oily woods. Pen mills will do that too. Sanding mills are easier to sneak up to the tube. The cast is not sticking too well but that can be overcome. Well, let me ask, is it like that after you cast it, or after you mill/square it to the end of the tube?

If it is happening BEFORE you square it, you are not getting good adhesion; if after, you are using too much pressure or dull cutter to get it squared and the resin is lifting from the tube. Could be heat too. IMO pen mills require pressure to do a decent job. That is why on another post, I was surprised that Woodpecker, a very high end tool company created a pen mill. In the long run they cause as much problems as they solve.

These are my experiences and opinions. Others are welcome.

Thanks for the information. I use a sanding belt to square up the blank and I use sharp carbide cutters. I see this after I finish the blank and start to put the pen togather. I do not use a pen mill but I am going to use between centers turning starting next week.

 

[jallan]

Seems to me that something is causing the separation either during turning or trimming. You might try using a sanding disk when trimming. Do you turn between centers? If so, the separation might be occurring when you tighten the tail stock. If turning with bushings, you could have debris in the tubes if the bushings aren't sliding in easily. Forcing them in could cause the separation. I have similar issues with PR and it's very frustrating.

Thanks for the information. I do not turn between centers yet but will start next week. What have you done to solve the problem. Sure could use the help as the watch part pens take a lot of time and money to make.
Thanks again

 

[Cwalker935]

I have not had the problem with liquid diamonds. With PR, I solved the problem by painting the tubes with fingernail polish rather than other paints. For printed labels, I coat the labels with clear Elmer's glue. I powder coat my tubes for watchparts and have not had any issues with watchparts and liquid diamonds.

 

[jttheclockman]

I am not sure what I am looking at. What are you coating the tube with before adding the watch parts?? Is the end of the tube where you see the tube chipped is that chipped out or is there still resin on top of that area??? Something is not adding up to what everyone is saying. There is more to this than that or I am not seeing what they are seeing.

 

[MRDucks2]

I am pretty sure what we are looking at is not chipping but delamination between the resin and the underlying surface.


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[jallan]

Yes it is not chipping

 

[Ed McDonnell]

If you are wet sanding then it may be water wicking into the blank. Sealing the ends of your blanks with thin CA after trimming and before wet sanding might solve your problem.

Ed

 

[Brian G]

Do you cast using a pressure pot? I learned with liquid diamonds that taking tube-in casts out of the pressure pot too soon causes big bubbles to form on the ends. Makes it look like delamination, but they were all of the microscopic bubbles joining hands in celebration of their release.

Now I leave liquid diamonds tube-in casts under pressure overnight, which ends up being about 24 hours. I seldom get to turning them until a few weeks later.

 

[jttheclockman]

That sure looks like it is chipped. If not chipping where did the material you used go to. What are you using to cover tubes?? Is it paint and if so what kind. More info is needed.

 

[jttheclockman]

Yes it is not chipping

You need to use more words.

 

[Kenny Durrant]

Did it look like that after demolding, trimming the ends or turning. If it looked fine after demolding then I would look at when it happened and when you started working on it. The first thing I'd question is how long did you let it set after casting? I and a few others let the resin cure for a week or more. Also epoxy resin doesn't like heat. If your cutting a bunch at once heat may be building up and softening the resin causing it to move. It could also be using too much pressure causing something to flex.

 

[ramaroodle]

I am surely no expert but it looks to me that there is a lack of adhesive/adhesion between the tube and the blank because the tube is smooth. There should be some glue residue on the tube if there was good adhesion IMO.

 

[MRDucks2]

As a watch parts pen blank it would have been cast tube in, not have the tube glued in.

One thing I have seen as I begin to play in this arena is similar damage from two things:
First is a presumption - the delamination is similar to the resin not attaching at the edge of molds due to cold molds.
Second: I have seen identical damage from pressing the pen together with even the slightest misalignment between the hardware and the tube.

Other thought: possible contact from Mold Release or such from either the plug when cast or a finger when mounting in the mold.

Just some thoughts.


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[ramaroodle]

As a watch parts pen blank it would have been cast tube in, not have the tube glued in.

Just some thoughts.

I figured that but it was just a thought. I was thinking that something as minor as oil from a fingerprint would keep the tube from binding to the acrylic. When you turn a tube in casting blank the tube doesn't just slide out when you turn it. It adheres to the blank. I was just thinking it could be an issue with the original casting.

 

[jttheclockman]

Well If the OP doesn't bother to respond then why waste our time. We have no idea what was his base coat?? Have no idea how it was applied.

 

[jallan]

Sorry

Sorry it took so long to get back but with Xmas and all. Sorry.. I paint the tube with Tamiya Color pint and let it dry 24 hrs. than glue on the watch parts and let it set for at least two days cast in Liquid Diamond in a ManEater mold and let it set for 24 hrs. Than sq. the ends with a belt sander 120 grit. after turning and sanding dry sanding is when I see the problem.

 

[More4dan]

I was wondering if you could plug the end of the tube and see if you could get some thin CA to fill the gap between the tube and LD from the end. Might be able to salvage the blank.


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[MRDucks2]

You know, Jerald, you may want to try casting some solid resin blanks or even tube-in in a colored blank. I may not work for a watch parts pen, but you could enter it in the Pretty Resin Pen Contest
Take a look at the rules for what is considered the fairest, best balanced competition for all members:http://www.penturners.org/forum/f18/pretty-resin-pen-contest-rules-157766/
I believe JTTheClockman plans to enter. You could show him how you can win with a pen made with Patience and that sometimes taking a little time is a virtue.