Square acrylic stock?

[BD]

First off - this site is great and I have learned a ton. You guys are great!

I am going to make my first hand cut stem and I am starting with square stock. I plan on it being a simple round stem. I suppose the best way to take the bulk of the material off would be a sanding disk. Then what? I don't suppose woodturning tools would work well on the acrylic but I have never tried it. Any suggestion? I will be using a wood lathe for the drilling of the stem and I do not have a metal lathe. (Not yet!!)

Thanks in advance for your help!!

BD

[KurtHuhn]

If you have a wood lathe, the best way to make it round is to use 1/8" or 1/6" cutoff tool and make it round a little at a time. Trying to make it round with a spindle gouge usually results in a shattered acrylic rod. Other than that, if you have a good eye, you can sand it round - but that's not too repeatable.

[Butch_Y]

One of the most important criteria for machining with acrylic is the cutting angle. A VERY sharp skew chisel (I use a modified spindle master from Sorby) applied at a negative angle downward rather than straight in from the tool rest will result in a much finer cut and also reduce the amount of chipping that can and will occur at a more positive angle.

Try with a scrap piece would be the best thing to do. I have machined plastics and acrylics for many years with great results using this method. Do be careful with applied pressure. This isn't wood and the material removed will be huge if too much pressure is applied. :naughty: Plastics and acrylics have a tendancy to suck in your tool. After a few passes you'll get the hang of it. I use old screwdriver handles for practice pieces.

Also, if you drill your airway first, you can then use a mandril of that hole size to assist you in a perfect round from that drilled hole. This is how pen turners get thier pens perfectly porportional.

Hope this helps.

[Heinz_D]

I also have a kind of wood lathe. To work on square materials I do some special preparation: Drill some centered helping holes in the ends of the material - 1.5 mm on the button side or a few mm with a bigger diameter for the tapper of the lathe and the complete airhole on the stummel side. Think of the filter chamber or a tennon if you want to have one! If you need a bigger hole for the lathe think about that you've to cut the length of this hole away later!

Cut the square material with a rasp, file or saw to a symetric hexa- or octagon (hexagon is easier). The holes must be centered and the hexagon must be symetric, otherwise you'll get an oval rod! Than use your lathe and a sharp tool to carefully round the hexagon to a rod. It's very useful to take a good bench of machine oil for working on acrylic material! Even for drilling holes! Be carefull while drilling and take of the drill bit often to get off the dust, use everytime a new drop of oil - that will provide the material to get hot and melt. Otherwise the material will adhere in the hole and it'll get bigger than you want to.

If you're using an additional tennon, drill the hole befor shaping the rod! I prefer to make my stems in one piece, but that could be more difficult: I only form the tennon on the lathe and then I do the shape with the stem on the stummel with a sanding disk...

If it's to difficult to cut the rod with a sharp tool you can use a rasp, a file or raw abrasive cloth, still with the machine oil, while the hexagon is rotating on your lathe...

To shape the raw stem I always youse a sanding disc with 100 grid. Acrylic is very temperature sensitiv, so have a look at that! For the fine work on acrylic I use some nail files and abresive cloth (240, 400 and 600 grid). Acrylic is rather of good nature for polishing. Even with some little scratches from sanding you can polish it with cleaning wax to high glossy surface. You don't need to polish with steel wool or anything else!

[bvartist]

I don't suppose woodturning tools would work well on the acrylic but I have never tried it. Any suggestion? I will be using a wood lathe for the drilling of the stem and I do not have a metal lathe. (Not yet!!)

I've only done a couple acrylic stems, but haven't had any problems shattering the ones I did. I use a very small 1/4 inch fingernail gouge on a wood lathe to turn the square stock round. Takes time and patience much the same as a small parting tool. I do think a larger gouge, or one with a flatter cutting surface would result in chips and breaks though.

David

[Nick]

I havent used square stock before, but wouldn't it be easier to round off the edges on your disk sander first?

[LexKY_Pipe]

I think that's what the guys who turn pen blanks do. Many pen blanks are square acrylic.

[Butch_Y]

I'm thinking a 45 degree router bit would do the job nicely. You'll get a bit of melt on the burr but a file will knock that off. Dont take too big of a pass and knock the burr off on each pass so as to keep the angle precise.

Please use your fence and watch your fingers.