Sandblasting Mask

[Mark Henry]

I am new to sign making and working with HDU and need some informtion on sandblasting HDU. Is it possible to carve HDU with the mask attached before carving? Has anyone used a drag knife to trace the masked pattern/toolpath then weeding it before carving, if so how well does it work? I do not have a plotter and I am trying to figure out the best way to do this. I will be using Hartco High tack mask because I will be using it on unprimed HDU. Thank you in advance for any advice.

Mark

[zeykr]

Either method (Routing or drag knife) works. When routing you need to make sure you have a bit that will cut the mask cleanly. I have done it both with a downcut and with a v bit. Routing does allow you to give more depth to the background.

With a drag knife you can place the mask on a vacuum table and cut, then apply. A combination of the methods can allow a multi level sign.

[Mark Henry]

Ken,
I appreciate your insight about this. I'm going to try routing it first and see how that works. My next question would have been which bit to use, thanks for addressing that question as well.

[GlenP]

Here is what I use to cut mask when attached to hdu on the bot. THis pic is one Joe C. posted once. They are round over or sometimes called beading bits come to a nice point and make a really nice cut with the sandblast mask. The one issue with hdu and cutting this way is hdu tends to not have a consistent thickness throughout the sheet. Just the way it is with hdu.....at least Duna which is what I use. The drag knife is spring loaded and will ride on the hdu and move up and down with the minor thickness variances. I don't have a drag knife and like using the beading bits. Works for me. :)

[Mark Henry]

Glen,
I appreciate the information. Will a 60 degree V bit work as well or do you prefer the roundover bits you mentioned?

[GlenP]

Hey Mark. The 60 degree bit will work I preferred the beading bits as they come to a nice point and made a clean crisp cut right on the vector.If you were doing smaller letters or fine detail the 60 vbit will make the vectors cut slightly wider as it doesn't come to as sharp of a point but it will work. For larger stuff especially. I also had a customer use a Precise Bit that I sell (EM2E8-0945-30V).
The bit isn't made for this purpose but it has a very nice point and my customer said it was the best cut he has so far with the cnc and mask. He has a drag knive and doesn't use it. I will pull a bit and take pic tomorrow to show you the profile.