bumps appearing in pens blanks after a few months

[Ric]

WARNING VERY LONG POST HERE>>>>More & more recently I have been noticing that bumps appear on the body of the acrylic pen blank a few months after I have finished them. So far it seems to be happening on "Aqua-pearls, & pearls" (PSI) I have a theory that it might be my fault by applying too much force when polishing, or polishing for too long at a time thereby increasing the friction building up the heat & the blank is separating from the CA adhesive.
In the past when I was a bit "Greener" I noticed that if I applied too much force on the polishing pad the heat would build up & a bump would form, so this is why I am thinking that the problem I mentioned at the first is a direct cause of my over exuberance.
Also I would be interested to know what others may consider an adequate amount of time to spend polishing to achieve the best possible finish you can. When I sand an "plastic" blank I use ALO paper up to 400 grit, then switch to WET/DRY to 600, then I use the micro sanding pad system that has the nine pads going from 1500-12,000 grit. On these pads I time myself to a minimum of three minutes of actual polishing time per pad, this does not include the time it takes to scrub the slurry off the pad & apply water on a regular basis while polishing, then if I like what I see with that pad, I move up to the next one. I continue in this manner until I am pleased that I have achieved the best possible finish I can. After I have buffed the blanks between polishings I complete the process with a minimum of three coats of plastic polish. I know this is quite a bit more than others do, but I maintain that I can tell the difference between someone who polishes his work for a minute or so per pad, usually getting bored or saying "that's good enough" long before they reach 6000 grit, let alone 12,000.
I apologize for the length of this post, seems I just get rolling,,,,& before you know it....
"if life hands you lemons...make mojitos."

 

[jttheclockman]

Hello Ric

Maybe I did not follow everything you said so I maybe well off base here. But why are you using CA on an acrylic blank??? No need to unless you are filling in holes. Next thing is learn to use a skew and you will be able to skip all the pre sanding till you get to MM. Then when you do those and hit the polish wheel you in my opinion just undid what you did with the MM If you are buffing on a buffing wheel how about trying to skip the MM and just use a buffing station with the proper compounds.

You buff or polish a blank till you see all the radial scratches gone. Some people go to extremes and use magnification but to me the naked eye is just fine. The polish or wax people use is a personal thing.

But if you have a system and it works that is just fine and if you think you have found your problem then that is also good. I have never heard of it happening. Not on this forum anyway. Months later they show up is strange. My original guess would be that being a mixture of different materials they did not sand evenly and from finger pressure you were not able to get them sanded equally. this happens alot when segmenting with different materials like woods and acrylics or woods and metals. Hence the use of a skew.
Good luck.

 

[thewishman]

Some acrylic blanks are soft and will take on the texture of whatever they are placed on. It gets even worse if the are very warm - like in a hot car or in direct sunlight.

Check to see if those pens also have dents where the clips are against the barrel.

 

[Sabaharr]

As for MM pads I wet sand with them as you do. I use the first pad about twice as long as the rest to get the major scratches and groves out then the rest I use for less than a minute each. My acrylics look like glass. Sometimes I use NOVUS to polish but very seldom.

 

[Ric]

Thanks John, If you do not use CA glue to adhere your tubes & blanks, then you could very well be using an epoxy or a polymer substance as an adhesive. I find that CA works well for me because it is fast & less messy than 2 part epoxy.
When I started making pens a few years ago in rehab, I had an instructor that was a fanatic when it came to using a skew. For the first few months when I started getting serious about this all I did was practice turning fir & other bits of scrap wood until I felt confortable using that item, in fact I still occasionally use it today especially on wood products, however about a year ago I discovered indexable carbide inserts made for pen turning & have not looked back since...If you want a clean even profile with a bit of a shine to it when turning, give that a whirl, I'm betting you'll fee the same as me about them...
I have a buffing wheel system set up that has the three different wheels on it, which I use for all my wood turnings, why do I use MM pads? Not sure I guess i just believed all the promo stuff that is in all the trade catalogues about them, just got comfortable using them, & have continued using them.
The reason I sand after cutting down the blank is to get that piece to the exact measurement where I need it to be to begin the polishing process. I usually stop cutting when I get to within .06-.1" of my desired diameter, I use my digimatic callipers constantly when I turn, checking every few seconds when getting close to my desired size, then I use ALO paper to get down to .04", then I start using the MM pads. I have done this so many times that I know that I will need a minimum of .04" to get the shine I am looking for. By the time I have reached 6,000 grit in the MM I am so very close to where I want to be, that using the last pads 8,00- 12,000 is not a problem because of how little they actually take off. I measure each & every piece that comes in contact with my blank to ensure that the fit is extremely tight. Nothing bothers me more than to run my fingers down the profile of a pen & feel where each little component starts & stops.
As far as ensuring the correct straight profile I also use a sanding board to ensure that every thing along the profile is as close to being the same as I can allow.
So John , this little bit of extra info I just provided for you, hopefully will provide you with a bit more insight as to my process, maybe you can think of something else I am missing or have not tried..Thanks again for responding, look forward to hearing from you again.
Regards Ric.
"IF LIFE HANDS YOU LEMONS...MAKE MOJITOS!"

 

[Ric]

THANKS Sabaharr, I'm not familiar with "Novus" well at least I don't think I know of it, I don't recognize the name, but I'll "Google" it to find out though...
Thanks my friend
Ric.

"iF LIFE HANDS YOU LEMONS...MAKE MOJITOS!"

 

[duncsuss]

... I have a buffing wheel system set up that has the three different wheels on it ...

But which compounds are you using on the wheels?

The "standard set" for wood (brown tripoli, white diamond, and carnauba wax) is not the best for acrylics, from what I've read.

 

[Ric]

Thanks Chris, I never noticed any dents where the clip tip contacts the body of the blank, but that might make sense if the pen got unusually warm from exposure to the sun or an alternate heat source. When finished I keep my pens in a clear plastic pen tube with al the correct information attached to it on a label.
These bumps are quite often near the centre band where the plastic is the thickest, that's where they start to appear months after I have signed off on the manufacturing of the pen.
Thanks again..Ric
"IF LIFE HANDS YOU LEMONS...MAKE MOJITOS!"

 

[Ric]

ooh..that is exactly what I have been using..I remember years ago when I (we) used to buy a box of buffing sticks made by Delta that had five different compounds in it ..perhaps I should investigate that a bit more..To tell you you honest truth I had completely forgotten all about that until this very moment when I read your "thread."
Thanks a lot Duncan, I think my light just went on....

"IF LIFE HANDS YOU LEMONS...MAKE MOJITOS!"

 

[jttheclockman]

Thanks John, If you do not use CA glue to adhere your tubes & blanks, then you could very well be using an epoxy or a polymer substance as an adhesive. I find that CA works well for me because it is fast & less messy than 2 part epoxy.
When I started making pens a few years ago in rehab, I had an instructor that was a fanatic when it came to using a skew. For the first few months when I started getting serious about this all I did was practice turning fir & other bits of scrap wood until I felt confortable using that item, in fact I still occasionally use it today especially on wood products, however about a year ago I discovered indexable carbide inserts made for pen turning & have not looked back since...If you want a clean even profile with a bit of a shine to it when turning, give that a whirl, I'm betting you'll fee the same as me about them...
I have a buffing wheel system set up that has the three different wheels on it, which I use for all my wood turnings, why do I use MM pads? Not sure I guess i just believed all the promo stuff that is in all the trade catalogues about them, just got comfortable using them, & have continued using them.
The reason I sand after cutting down the blank is to get that piece to the exact measurement where I need it to be to begin the polishing process. I usually stop cutting when I get to within .06-.1" of my desired diameter, I use my digimatic callipers constantly when I turn, checking every few seconds when getting close to my desired size, then I use ALO paper to get down to .04", then I start using the MM pads. I have done this so many times that I know that I will need a minimum of .04" to get the shine I am looking for. By the time I have reached 6,000 grit in the MM I am so very close to where I want to be, that using the last pads 8,00- 12,000 is not a problem because of how little they actually take off. I measure each & every piece that comes in contact with my blank to ensure that the fit is extremely tight. Nothing bothers me more than to run my fingers down the profile of a pen & feel where each little component starts & stops.
As far as ensuring the correct straight profile I also use a sanding board to ensure that every thing along the profile is as close to being the same as I can allow.
So John , this little bit of extra info I just provided for you, hopefully will provide you with a bit more insight as to my process, maybe you can think of something else I am missing or have not tried..Thanks again for responding, look forward to hearing from you again.
Regards Ric.
"IF LIFE HANDS YOU LEMONS...MAKE MOJITOS!"

Hello Ric

First let me say that you can ask 100 people their process of finishing a pen and get 200 answers. I did not realize you were talking about gluing tubes in with CA I thought you were adding CA as a top coat on acrylics. That is fine I do use epoxy and always will. I will never use CA it is too brittle for me.

Next thing is I use a carbide cutter for certain things but always finish with a skew. Did you know you sharpen a HSS steel tool sharper than carbide??? That is fact.

As far as all the other stuff to me you are wasting your time. sanding when a skew will get there just as fast and accurate. Every sanding step adds radial scratch pattern that must be removed with the next grit size. Too much work for me. As for MM and polishing again to me is a process that is just not needed. Do one or the other. and the results will be the same.

If the process works for you then continue doing it. As far as the bumps I have no other answers because the 10+ years I have been making pens I have never heard this. Hopefully someone with more info can help. The strange thing is this occurs months later so heat from sanding and polishing can be eliminated. heat from a car or other source maybe but boy I am not convinced. Good luck.

 

[Bikerdad]

WARNING VERY LONG POST HERE>>>>More & more recently I have been noticing that bumps appear on the body of the acrylic pen blank a few months after I have finished them.
"if life hands you lemons...make mojitos."

Acrylics are susceptible to solvents. The fact that the bumps are appearing months after you finish processing means its highly unlikely that your finishing process is the cause. It's much more likely to be an environmental factor, most likely either something in the air or something blanks have been coming into contact with, although it's remotely possible that you're getting a very slow reaction between the CA and the blank itself. You give no indication of what sort of existence these blanks have been leading in the interim, that's what I'd be looking at....