Learning Bits

[Dranos]

Hi folks,

I'm just about up and running with my new Shopbot. This is indeed a very helpful forum. Truth be told, I'm totally new to the world of CNC and simply am clueless when it comes to many things that may come as second nature most persons here.

Take the bits for instance. I have a starter kit with bits:
37-82
48-005
48-072
52-910
57-910
65-025
77-102
91-000

I have been to onsrud.com to learn what I could about each bit but found the site vague as many of the bits work with a wide range of materials.

For my immediate needs I will have to cut letters from 1/2" PVC, 1/2" Alumacore along with various designs from 1/4" foam board, 1/2" Sintra, 1/4" coroplast, 1/4" Solitex and 1/4" acrylic (plexiglass).

Can someone advise me on which bits to use on each substrate? Once I get pass my irst set of jobs I will have time to experiment but for now I have to learn fast to meet my current deadlines.

Thanks in advance.

[signtist]

Your most popular bit will be a 1/4" down cut. I use this for most sign shop stuff.
I use Onsrud 62-775
John
www.signgraphic1.com

[toych]

As a reference you can go to plasticrouting.com and search each substrate by brand for a suitable bit.

You will need to order bits for the plastics to get the best results.

There is also starting points for speeds and feeds.

Your hold down method will be critical to good results as well.

Don't be intimidated, this is fun stuff, once you make a few good cuts you'll be willing to tackle anything.

[tuck]

Adrian,

You're gonna make your share of mistakes with bits and feed speeds. We all did and it's just part of being a novice. All of the research in the world won't stop you from grabbing an down-spiral thinking it was an up-spiral and possibly ruining some material. It comes with the territory.

My best advice is to save all of the scrap material you can to practice on, seeing what works well and what don't. And fear not! You'll figure it out quickly and keep mistakes to a minimum.

There are dozens of different substrates and hundreds of different bits as well as almost unlimited feed speeds. Just ask on this forum project by project while you're getting going and you'll get plenty of help.

[fredtoo]

Jump on the Onsrud web site and request a catalog. There's a lot of info within, not too readable but it will tell you what that bit is you're holding in your hand.

[knight_toolworks]

I would not use a dowcncut with any of those. they will help hold the parts in place but they will also leave a lot of shaving stuck to the edge. acrylic is a upcut or a straight bit only for thin material I like a straight bit to keep from lifting the material.

[joe]

Steve,

Have you tried a Belin?

[Dranos]

Thanks guys. Somehow my email notification was not enabled on this post so I didn't even know I got replies. I have made some successful cuts and I'm really excited about the possibilities. I'll be sure to check the resources mentioned and post here if I need more help.

I have no clue when to use an upcut vs a downcut. I also don't know when to change the speed. I'll try and experiment some more.