IMG_1962.jpgIMG_1963.jpgIMG_1967.jpgIMG_1968.jpgIMG_1969.jpgI purchased a used shopbot a couple months ago for my start up business. I intend to use the machine to cut out small parts from HDPE and MAPLE hard wood. I havent been able to achieve a smooth finish from the day i got it.

I am trying to product parts to a board rack called, the gnar bar. Here is my website so you can see the application side a bit more (royal-racks.com). I bought the machine to cut these pieces out of hdpe and maple hard wood. I have 4 parts I am looking to cut out of each material:



2 End caps (left and right)
1 Back Plate (mounts to the wall)
1 center piece (holds the bar to the backplate)

The end caps are to be cut out of 1" thick Densetec from Sabic (BLACK), and 1" thick Maple Hardwood.

The Back plate is to be milled out of 1/2" thick densetec from Sabic (BLACK), and 1/2" thick Maple Hardwood.

The center piece is to be milled out of 2.5" thick Densetec from Sabic, and 2.5" thick maple hard wood. ( we are milling half, then flipping to mill the rest)

What I have been using for a cutter is the

Onsrud 63-783 3/8" single flute o spiral

I have been using this for both materials and have played with a 1/4" double flute up spiral from onsrud on maple.

Again, I have not been able to get a smooth finish for the life of me, i have tried faster and slower feedrates from 1in/sec to 3in/sec with and without a finishing pass taking .03, conventional on wood, climb finish on hDPE. I STILL cannot achieve a smooth finish.

I replaced the brushes and bearings in my 7518, but we did have the worry that maybe we were getting chatter because the motor is worn out? or is it the fact that i have not found the right feedrate yet? everything i have ran has been at 16,000 rpm.

I also have an issue when i run pockets on these parts because it move the cutter so slow and then all of a sudden just jerks into full speed. I have also noticed it melting the hdpe in this case and that cannot happen.

I would really like to get on the phone and just go over everything, from feed rates, to plunge, to crossover. I need to get this thing dialed in so i can start my company and pay expenses, but i cannot seem to achieve a smooth finish. Is it the feed rate? is it the bit im using? is it my router?

also, when i do a pocket tool path, the bit sits in the same spot for way too long causing heat and melting of the plastic, is there a way to program around this or is this a cross step % issue?

are these ridges from a worn out motor? the wrong tooling? the wrong feeds and speeds?

I have included some photos of my trials, please help me, Im becoming annoyed and this is just the start, I cannot wait to get into production and custom engraving!!!

thank you very much for your time, I certainly hope you can help me in the right direction.

Thank you,

Brandon Bauer
Brandon@Royal-Racks.com
608.630.0153