Correct allowance for painting inside of Acrylic blanks

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Tiger

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Haven't made an acrylic for some time and prefer timber as less problematic for me anyway but thought I'd ask the wise heads here. I made 2 acrylic pens and painted the inside of the tubes on both barrels, I used JR Gent pen kits. I used the recommended drill bit which was a precise fit for the brass tube. I then with some sandpaper and dowel expanded the barrel to allow for some paint, the brass tube was now a very loose fit and easily slid through the blank. So after painting the insides of the blanks the lid part of both pens shows very slightly the brass tube which means that some scraping of the paint must have occurred whereas the bottom parts of both pens has no scraping. I didn't notice any paint scraping when inserting the brass tubes and used 5 min epoxy to glue the tube into the blanks. Question is what sort of gauge, if any, can be used to determine more accurately that there is enough allowance for painting inside the blanks? By the way I used acrylic paint on one blank and nail polish on the other, this seemed to make no difference although the nail polish dried much quicker.
 
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I don't even bother to sand the inside of the blank before sanding and I've never had a problem with the tubes being too snug. My paint of choice is Tamiya acrylic model spray paint. I've had trouble with other paints peeling, enamel in particular, but never with the Tamiya acrylic.
 

jttheclockman

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Impossible question to answer. Every kit is different. Everyone paints differently with amount of paint used. Not everyone uses the same paint. I like to spray when possible. If it is an acrylic blank that I know has transparency I always sand the inside of the blank. I never paint the tube. That is a waste of time. May add some color to epoxy when gluing. Only time I will paint tube or worry about tube is when clear casting. No need to paint if using woods. Becomes an experience thing. Do a few 100 and you have experience. Pen turning is not rocket science. Just a matter of doing them and you learn from each one you do. A good set of numbered and letter bits is a key. Harbor freight set is a good starter set and go from there. Happy turning.
 

Kenny Durrant

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I use the recommended drill for the kit and drill the blanks. I use a water base acrylic brush on paint and paint the inside of the blank with a Q-Tip. Then I use the Foaming Gorilla Glue and put a layer inside the blank and on the bare tube. I've noticed that sometimes it's a snug fit when the paint is dry but when the glue is applied it slides in smoother. I also like to see the paint tint the glue so, in my mind, it seems to coat everything.
 

TonyL

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I have painted hundreds of tubes and barrels (probably more like 2,000). Only once did a painted brass tube fail to fit inside a barrel. I don't make any modifications or adjustments to the hole size - I use whatever drill bit is recommended. I happen to use spray paint, but have used, Testors, Craft paint, etc. and enjoyed the same results (I just happen to prefer Krylon/Rustoleum). I only use epoxy when gluing painted tubes and barrels. Psychologically or , in fact, it appears to act as a lubricant. This is not a recommendation, just what I happen to have good luck with based on trial and error. Happy turning!
 

More4dan

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I use spray paint also and if I wait a day to dry, I have not had an issue. I also chuck the freshly painted blank in my lathe and spin at max rpm. It leaves a very smooth and consistent layer of paint in the hole. I've used acrylic paints and a paint brush and almost all have experienced scrapes.


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TonyL

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I should have added what Dan said - I, too, wait very close to a day to dry.
 

More4dan

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I also plug the end of my tube with clay which might also limit the scrapping of the painted blank. I add glue from the opposite end of the blank to the hole and on the tube. Very sloppy and "wet" so the tube goes in with little resistance.


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Charlie_W

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I usually use a drill bit that is ten thousandths larger than the tube. This will allow for spray paint in the blank.

Also, I have found that tubes will have a sharp edge which becomes a very effective scraper when inserting.....which you don't want. I use a fine flat file and remove the sharp edge/burr from the end of tubes.
 

Tiger

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Thanks for the responses, I think it might come down to my technique of inside painting, it just seems to go on too thickly in parts. Dan I will give that spinning on the lathe a try and see if I get a more even coat. Charlie 10 thous is a good guide and something that is easy to verify and repeatable.
 

Charlie_W

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Thanks for the responses, I think it might come down to my technique of inside painting, it just seems to go on too thickly in parts. Dan I will give that spinning on the lathe a try and see if I get a more even coat. Charlie 10 thous is a good guide and something that is easy to verify and repeatable.

As John mentioned earlier, get a large set of bits with fractional, number and letter sizes.......and digital calipers makes life easy.
 
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