finishing acrylic?

[Rick Gibson]

Going to be trying my first acrylic acetate blank later today, anything special I should know about finishing it before I start?

The drilling went ok but it sure stinks.

[gwilki]

Rick

I find finishing acrylics a heck of a lot easier that wood. What you do depends a bit on just what the blank is. There are acrylics, resins and acrylesters and a bunch more. I generally sand to 4000 MM. All sanding is done wet. Then, I polish with some combination of brasso, novus 2 and novus 1. Sometimes, I apply some conservators wax just to keep fingers prints off.

Many sand to 12000 MM, but I find that, if I'm going to use polishes, there is no point going beyond 4000. You can also simply sand to 12000, and get a nice finish on some plastics.

I think one of the keys to getting a good finish with as little effort as possible is not to start sanding at too coarse a grit. Depending on how you turn the blank, you can start at 400 wet or even 600 wet. If you start more coarse than that, you end up putting scratches in, only to have to take them out again.

I hope this doesn't create more confusion than it remedies.

[Rick Gibson]

Thanks Grant. That's pretty much what I needed to know. I much prefer working with wood, don't like the smell of the acrylic as it's worked and working in the basement I can smell it all over the house. The buyer saw the round top european on the Wm. Woodwrite site and wanted that particular blank. Since he is paying for it that's what he gets.

[gwilki]

You're welcome, Rick. I saw the pen you did. It really looks good.

One other thing that I've found in working with acrylic is that LV's brad point bits can be a bit too aggressive. I tend to start the hole with a brad point, just to make sure that I am in the center of the blank. Then, I go to a normal chisel point HSS bit to drill it through. For the larger pens, Emperor, El Grande, etc., I squirt water into the hole as I progress. You risk melting, otherwise, and the hole can be out of round.

Of course, YMMF. :)

[Marcel]

Hi,

I disagree about the brad points.
I used to experience blowouts with my acrylics when using normal pointed drill bits. Since I switched to brad points I've never experienced a blowout at the end. Also make sure you drill a bit at a time and clear the bit of the acrylic in the flutes, it tends to get stuck. I use a small plastic or brass brush to clean the bit. I drill maybe 1/4 to 1/2 inch then raise the bit to clean and add water in the hole. That method works fine for me, but ymmv so adjust for your style.

And a slower speed than you would use for wood is required so you won't overheat. The smell you say you got means 2 things: You need better Dust collection for all fumes ;-) and you are overheating your blanks, slow down and you will get better results and less stink.

Important: You do need to use water when drilling and when (wet) sanding.

I start my sanding with the 1 500 MicroMesh then go through the grades up to 12 000. I then use the HUT plastic polish (basically any automobile paint fine scratch remover should work, such as the turtle wax fine polish paste (white)).

And I finish with a coat of Renaissance wax.

Don't sand at full speed! you'll burn the coating of the MM (damhik)
With acrylics, as mentioned by others, heat is your biggest concern when drilling and when sanding. The finer the grit, the slower you need to go.


Have fun,

[Rick Gibson]

Marcel I'm running my drill press at it's slowest speed so can't slow it down. My biggest problem here is I can't drill all the way through the blank with the drill press I have. I drill as far as I can go a little at a time then I have to stick a block under the vise to raise it. Works ok with wood but not the acrylic.

Started wet sanding at 400 grit and worked my way up to 1500 lath speed at 1800. Then I used a strip from a paper bag. Grant mentioned brasso and I didn't have any but I did have silvo the silver polish and gave it a try. Worked great. Tried the silvo later on a blank with CA finish it came out better than using the buffing wheel.

[Colin Gregg]

rick, i do it the way marcel does it, and find you do not need the paper bag at all on acrylics.

[dalemcginnis]

As far as drilling your blanks, have you thought about doing that on your lathe? I have the same problem with my bench top drill press, also I could never seem to drill a hole straight through the blank.
On the lathe it is real easy to pull the bit out of the blank no matter how deep you are. Also since I am drilling the blank before cutting it to length I don't have to worry about blow outs, though I haven't seen that happen when I go completely through the blank anyway.

Typically what I do is put my blank in the chuck and drill as deep as the bit will reach. Take the blank out and cut off the section for the first tube. Put it back in the chuck and finish drilling, then cut the second piece to length. I do the same with either square or round blanks, If the blank is not square I put it between centers and round it first. I have also found that I don't have to find the center of the blank first as the chuck lines it up automatically.

[Rick Gibson]

I've drilled on the lathe Dale but not pen blanks. Never really thought of it. I'll give that a try and see how it works for me. Thanks.

[ACAPET]

In theory, drilling on the lathe is the best way to get perfect alignment - you can drill a hole in the estimated centre of any misshapen log or non-geometric offcut. The problem is chucking if the wood is not already perfectly round or square. My method, which dispenses with chucking, is the following:
-punch a small centre hole on both ends of the blank - the centres being the best estimate you can figure out if the blank is terribly misshapen, or with bark, etc.
-install a Jacobs chuck in the head stock with a wood drill a fraction below the final size (eg 6 mm or 1/4" if you want a final 7 mm diameter)
-rest the blank between the point of the drill and the tail stock with a 60° centre. Retract the tailstock sleeve completely.
-if you feel nervous, lock a Vise Grip or similar gently around the blank. One stem of the Vise Grip will rest on the lathe bars, preventing the blank for turning. More confident turners can of course hold the blank by hand (not recommended in case the blank cracks under the stress)
-start the lathe at the appropriate speed for the hole diameter
-crank the tailstock sleeve, forcing the blank into the drill. Retract it often to clear the waste. Reach into half of the blank and turn the blank around
-drill the remaining half from the opposite end
-when the two holes meet, stop the lathe and remove the blank
-insert the final size drill (not a brad point one, but a metalworker's one, with conical end)
-start the process again until half the length is reached
-this time however, do nor invert the blank
-retract the whole tail stock completely so that it is out of the way
-holding the blank by hand (wearing a thick leather glove is in order) gently push the blank through its whole length until the bill protrudes. Removing the final millimetre or 32nd exerts no great resistance even in the hardest woods.
-any irregularity should be in the middle, invisible part of the blank

[bohdon]

-crank the tailstock sleeve, forcing the blank into the drill. Retract it often to clear the waste.

Doesn't the blank fall off every time you retract?
Also maybe I'm doing things backward but I usually cut my blanks before drilling them, it sounds like you're drilling the whole blank at once.



retract the whole tail stock completely so that it is out of the way
-holding the blank by hand (wearing a thick leather glove is in order) gently push the blank through its whole length until the bill protrudes.

The glove part...ouch! That may not be the best idea. I would rather drive the drill into my hand than to get a glove caught on a spinning shaft. IE: The spinning drill bit.

I wear latex gloves when I'm finishing, but I hope that the glove will rip off my hand with no damage if it ever does get caught.
I used to wear a leather glove when milling my ends....not any more.

FWIW I do think that the lathe is the best way to drill a blank. That is if you can trust the tailstock alignment on it.