View Full Version : Cutting 3" thick ash

Jeffrey Freedman
07-15-2003, 12:11 PM
Does anyone have any experience using a Bot to cut into ash wood, up to 3" thick? I have an application that involves cutting letters and numbers into a piece of ash wood. The job requires that these letters are approximately 3/4" wide and 1" high and must be carved in fine detail (a maximum of 10 letters or numbers per cut) and must go right through the wood. I presently use a computer controlled jig saw (I key in the letters or numbers, cut a small hole in the wood, put the blade through the hole and then secure it on the bottom) to do the job but it takes up to an hour to do a cut and the letter/number cuts are a bit uneven. If anyone has any experience using a Bot (or any other device) to perform this application, I would appreciate your feedback.

Thank you very much.

07-15-2003, 02:19 PM
You can do this on the bot in probably 1/4 to 1/2 the time (maybe quicker). You will need to do multiple passes depending on your bit cutting length. I am guessing that you'd do 3 or 4 passes (3 or 4 profile cuts at 3/4" to 1" cutting depth per profile pass) over the entire group of letters.

If the letter profiles are to be domed, then you will need software for doing 3D design and toolpathing. Otherwise you can do this on a SB right out of the box. I'd recommend using a 1/2" upcut spiral with an overall length of 5". ShopBot should be able to help you find the right bit through Onsrud Cutter.

Hope that helps,

07-15-2003, 02:59 PM

I thought the same thing. Then I wondered how I was going to get the detail in a 3/4" wide 1" tall letter.... with even the Grerber 1/4" X 2" bit....

Those are some deep cuts for some small letters.


07-15-2003, 08:31 PM
I just re-read "3/4 X 1"....

Those are some mighty small letters at that thickness!

Jeff, are those dimensions right?


07-16-2003, 01:53 AM
I am more interested in the CNC jigsaw that he talks about. Sounds like he is already using the right tool for the job. I am not hung up on the idea that the SB will do everything better than anything else - in this respect, I think that the hype around the SB is its worst enemy.

Jeffrey Freedman
07-16-2003, 09:10 AM
Thank you all for the replies.

1)Yes, the dimensions are correct. The letters are about 3/4" wide by about 1" high.

2)The problem with the CNC jigsaw is that it takes close to an hour to do the cuts and the cuts are a bit jagged. I was hoping to find a device that would do the cuts quicker and more precisely.

I've researched a number of different options (including CNC milling machines) and I've even gone so far as to talk to University engineering departments to see if they would be interested in building me an improved CNC jigsaw but so far, no takers.

I was also thinking about the possibility of the following:

Get a couple of Bots with different bit sizes in each one. Let the first one do the initial cut and then use the second one to do the finer cuts. However, I'm concerned that there will be some alignment issues plus the second cut still requires that the cut goes close to 3" deep. This will present a problem for the bit since it needs to be thin and long, cutting hard wood, which probably means that it will snap quite easily.


07-16-2003, 09:54 AM
Jeffrey, I might be able to help you improve your current jigsaw setup. Could you mail me some photos & more information please? gerald@scapenotes.com (mailto:gerald@scapenotes.com)

07-16-2003, 11:58 AM
Alignment of two heads on one machine is a small nightmare letalone two different machines.

We've been finding it easier for one off stuff to use one head to rough, change the bit and clean up the details.

07-16-2003, 01:19 PM

Yes I have cut 3" Ash, on larger size jobs with little detail it is possible with many passes. The small letters 3" thich with fine detail I would pass the job up.

Cutting 3" ash you would need at least a 1/2" cutter, when this Mother kicks into end grain it will probably break the letters or move them, how fine a detail are you looking for?


I have set my two heads using homing sbp file incorporating (VI) command. I have two file saves as custom cuts for switching from 1 to 2 and another for switching from 2 to 1.

I cut a square or rectangular goove in a scrap pc of ply with one head and the another smaller square or rectangular goove with the other head, this will determine the offset. I then measure the distance between each groove on the X & Y axis, I then half the differece and use this size to refine the dimensions in the VAR settings to the custom cut file.

'Metric. Change Z1 to Z2
J2, 20,10

VI,,,,,,,4,3 'This line makes the switch
&NEWX=%(1)-206.00x 'Make VAR adding offset to the AccX axis to current location
&NEWY=%(2)-6.92y 'Make VAR adding offset to the AccY axis to current location
&NEWZ=%(3)+AccZ 'Make VAR adding offset to the AccZ axis to current location
VA, &NewX ,&NewY ,&NewZ @This line updates the location
'...Now do some work using the No.2 Z axis
J2, 0,0
SF, 0

Once you have messed around with the grooving changing over is very simple and accurate.



07-16-2003, 03:16 PM

The lettering would have to be pretty good. If you post an e-mail address, I'll e-mail you some photos of what I do with the existing setup. Or you can send me an e-mail, jfreedman@gentek.com (mailto:jfreedman@gentek.com) and I'll e-mail you.


07-17-2003, 01:35 AM
Are you cutting wording into baseball bats? Perhaps a laser would do a better job on small lettering. Of course, it would probably have to be a prohibitively expensive laser to cut through 3 inches of ash wood...

Trent Busch
07-17-2003, 11:05 AM
I don't think a router will ever work for this application, CNC or not. The bit size would have to be so large for 3" deep cutting that the letters would be unreadable.

You might be better off cutting 3 - 1" pieces on a CNC scroll saw and then laminating them together. A shopbot would work for this method with a small cutter and many step cuts.

If its a baseball bat, you might have to cut half way through, rotate the bat, and cut the other half in reverse. The bit size will still be a problem.

I think I have seen a CNC waterjet do projects like this, with abrasive media. There are custom shops everywhere.

Jeffrey Freedman
07-17-2003, 05:40 PM
Thank you for the replies.

Yes it is a baseball bat and I was also thinking of flipping the bat but I was concerned about the alignment issue.

I've spoken to some waterjet people and so far, I've been told that the waterjet machine will only do about 1". In addition, I was told that the abrasive media does not make very neat cuts in hard wood like ash.

Thanks again to everyone who replied.


07-18-2003, 05:24 PM
You could try a 1/8 end mill, I have cut 1 1/4" mdf - 4 passes to get through. Perhaps drill some 1/4" holes through the bat for positioning then cut 1/2 way through, flip it and reverse the cutting file.

07-18-2003, 09:18 PM
Hi Jeffrey.
Just my 0.02 $CDN worth. Have you looked into an EDM setup? This might serve your purpose if you have a large enough order to offset costs.
Like I said, just my thoughts


07-18-2003, 11:03 PM

Please tell me what EDM stands for and a link, if possible.



07-18-2003, 11:13 PM

I am trying to hallow out a rectangular shape that is 8 inches long 1-1/8 wide and 1 1/2 inches deep, but I need the the depth to be on a 5 degree taper so that the bottom of the hallowed out rectangle is smaller than the top. Can anyone tell me how to do this.


07-19-2003, 12:39 AM
Ron, the EDM that I know for cutting thick material is Electrical Discharge Machining, or alternatively called spark erosion or wire cutting. The material needs to be electrically conductive in order to work - wood does not work.

Carrol, two possibilities:
- Get a tapered cutter
- Run multiple passes, each getting slightly deeper and smaller, and sandpaper smooth.

07-19-2003, 07:39 AM
MSC sells bits with a 5 degree taper....If my thinking is correct your profile would then automatically be what you're looking for...
As an alternative Artcam Pro lets you add "draft" to a file so you can remove parts from a mold more easily..

07-19-2003, 07:54 AM

I have just never known of EDM cutting of wood. If Perry knows of a method, I am curious and would like to know.


Gerald and Bill are right about the tapered cutter. Almost any large industrial machine shop supply will have them.


07-19-2003, 07:57 AM
Carrol may be needing a 10 degree cutter to cut 5 degrees on each side?

07-19-2003, 07:30 PM
Sorry guys, I had a brain f*rt. What I really was thinking about (but I doubt would work) is maybe a hot wire. Same mechanics as EDM (single wire slicing through material) but a different principal. You are quite right, EDM is not for this application. I don't know if a hot wire would work with wood well. On plastics it works fantastic!
Once again I appologize for the confussion.