Acrylic glue problems

[papNal]

I'm suddenly having trouble keeping the tubes in some of my acrylic blanks when I start the final pen mill cleanup and squaring.I'm using Testors model paint to color the blank hole,letting them dry overnight,usually in my dehydrator, then glue in the tubes normally using 5 min. epoxy,then another night of drying.Today had two tubes to pull out stuck to the pen mill shaft.The paint looked still soft,any ideas or advice on better way to glue will be much appreciated. Thanks John

 

[toddlajoie]

Every time I've had that problem it was caused by either old glue on the pen mill shaft from a previous pen, or still tacky glue on the inside of the new pen tube. I don't use 5 min epoxy, so I can't say for sure if it would stay tacky for that long or re-soften under heat like Sumo or CA can.

 

[Displaced Canadian]

I had problems with CA and acrylic so I switched to gorilla glue and haven't had a problem after I changed.

 

[Mac]

Did the paint stay on the tube or blank when it released? How thick do you paint it? Ever thought of mixing the color and epoxy and do all at one step. If you are getting a real smooth finish when drilling the hole you might want to sand the hole before you paint so the paint can hold on to the blank. I use a Qtip to paint with. I use one side to paint and the other to remove any that I Don't need. Don't know if any of this will help or not.

 

[papNal]

Did the paint stay on the tube or blank when it released? How thick do you paint it? Ever thought of mixing the color and epoxy and do all at one step. If you are getting a real smooth finish when drilling the hole you might want to sand the hole before you paint so the paint can hold on to the blank. I use a Qtip to paint with. I use one side to paint and the other to remove any that I Don't need. Don't know if any of this will help or not.

Some of the paint came off on the tube,I put the paint inside the blank with a Q tip and tried to just get a thin coat in the blank.I had thought of trying to color the epoxy,but thought someone on IAP had said that they had trouble with the epoxy curing,but I think they were using an acrylic paint.I was using Sumo or Gorilla glue,but one of the blank vendors recommended not to use an expanding type glue because of possible blank cracking.I had not had that happen,but decided to go to epoxy.On acrylics where the tubes either don't show or showing doesn't matter I have been using thick CA with no problems.Guess I'll try coloring some epoxy and just let it lay out and cure and see if it'll harden. Thanks for the replys everyone.John

 

[ldb2000]

You problem is most likely heat . You have some dried glue on the trimmer shaft or in the tubes and friction caused by the rubbing of the shaft in the tube is generating heat that is softening the glue that is/was holding the tube in . When the tube gets hot enough the glue bond breaks and the tube comes out , stuck to the shaft .
Clean your trimmer shaft and the insides of the tubes and your problems will go away .

 

[jttheclockman]

My guess is the paint did not dry. I use epoxy and also Testors paints on all my acrylic blanks and have not had one pull apart

 

[RussFairfield]

As a follow up to what Mac said. Both the paint and the epoxy are relying on a mechanical bond to each other and to the plastic and brass. There is no chemical action at the interfaces. If the plastic has a high polish, the paint won't stick. If the paint is a high smooth gloss, the epoxy won't stick to it. If the brass tube has a lot of oxidation or body oils from handling, the epoxy won'y bond. Try buffing the surfaces with some 280 or similar grit and give everything something to bond to, and then don't touch any surfaces with your fingers. I solved a similar paint problem by going to spray-can primers that leave a rough surface without sanding.

 

[knifecut]

I had that happen with CA so bought some epoxy; happened again. Even after waiting a few day.

The tip to the epoxy syringe broke, so had to toss it. Went back to the CA and it worked fine.

Tubes were painted with Valspar spray on enamel.

 

[randyrls]

John; Check for glue inside the tube or on the pen mill trimmer. Heat will cause the paint to soften. It isn't that it isn't dry, heat will just make the paint soft. Make sure you are roughing up the brass tube so the glue makes a good bond with the tube.

 

[papNal]

Thanks for all the help.Seems like heat might be the culprit,I tried to clean the trimmer shaft,even been waxing the shaft,also I always sand and rough up the tubes,I'll also try the rougher primer.I'll get it yet with you folks help. John

 

[RussFairfield]

Using the 5-minute epoxy could be your problem. A common problem with epoxies is not getting the 2 parts mixed thoroughly. By the time the 5-minute epoxy is thoroughly mixed, there is almost no working time left; and using an epoxy that is starting to cure will cause both adhesion and strength problems.

I suggest slowing down, switching to a 30-minute epoxy, mix it thoroughly (2-minutes), and letting it cure overnight before turning. You can mix a batch in a plastic cup and glue several pen blanks at a time.

 

[jttheclockman]

Using the 5-minute epoxy could be your problem. A common problem with epoxies is not getting the 2 parts mixed thoroughly. By the time the 5-minute epoxy is thoroughly mixed, there is almost no working time left; and using an epoxy that is starting to cure will cause both adhesion and strength problems.

I suggest slowing down, switching to a 30-minute epoxy, mix it thoroughly (2-minutes), and letting it cure overnight before turning. You can mix a batch in a plastic cup and glue several pen blanks at a time.

There you go. I think Russ hit this one. I was trying to figure out why I never had a problem using epoxy and testors paints. I do use a slow curing epoxy and will never turn a blank untill after at least 24 hours of drying.. That could very well be the answer in that the epoxy is both setting too fast or the mixture is not complete. Somethings to p[lay with anyway. Good luck.

 

[papNal]

Thanks again,I'll go to the slower setting epoxy,I let the 5min. stuff cure overnite any way so the speed is not important.As usual most thing fast acting sacrifices other things in this case (for me) strength. John