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We have a new CNC router. We are having a problem with breaking bits for cutting out MDO -3/4" thick, shapes. We do multiple passes. We have been breaking 1/4" thick carbide, double flute, upcut endmills. We have slowed the machine down to 25" per minute. The bits are not burning the wood. On our old, home built CNC router, we were able to use 1/8", carbide double flute, upcut endmills at a faster speed without breaking. Any suggestions as to what brand or what type of bit to use. We never go more than 1/4" deep in any one pass.
Diane Balch
-------------------- Balch Signs 1045 Raymond Rd Malta, NY 12020 518 885-9899 signs@balchsigns.com http://www.balchsigns.com Posts: 1695 | From: MaltaNY | Registered: Jan 2000
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Diane, we've never broken a 1/4" bit in wood. We cut at 75" per minute. My first guess would be that the plunge speed is too high. The second guess would be that the feed rate acceleration is too high. What is your plunge rate?
I haven't been following the site very closely in recent times. Have you done a post on the features of your new machine?
The few 1/4" bits we have broken on other materials were usually caused by pinches caused by the material moving on the table or scrap moving around and grabbing the bit.
Hope this is helpful. Vic G
-------------------- Victor Georgiou Danville, CA , USA Posts: 1746 | From: Danville, CA , USA | Registered: Dec 1998
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The acceleration is set fairly low. The bits just seem to snap off and the router continues on like nothing happened.
We have been using solid carbide Enco spiral metal cutting bits. The Onsrud tech blamed the shallow collet on the Porter Cable router. He said 50ipm with a depth equal to the bit width would work best.
We just ordered a variety of new bits to try.
ernie
-------------------- Ernie Balch Balch Signs 1045 Raymond Rd Malta, NY 518-885-9899 Posts: 405 | From: Malta, NY | Registered: Jan 2003
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There are so many potential answers. I wish I could give only one. Listed below are a few possabilities. I have made every mistake you could do on my CNC.
Please look these over:
Change the collet, check to see if the bit is not slipping. Make sure the rpm is correct as too slow a motor speed will break bits.
Try a standard double fluted strait bit. Theory aside, standard bits sometimes will shear material cleaner.
Use a 1/2' bit on the first pass and come back for a finish cut with a 1/4".
I can't wait to hear your solution. Your new CNC will work fine when you get past this little hickup.
Happy routing,
j
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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I've been lucky thusfar and only broken 3 bits in 2-1/2 years. Like Amy, Belin spiral O's have worked on nearly everything we cut. But I have to admit I haven't cut any MDO so I can't offer any useful advice. I'll keep an eye on this post to see what the solution is.
-------------------- Bob Stephens Skywatch Signs Zephyrhills, FL
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I never considered a slipping bit in the collet. I know I was getting a squeal as the wood cut. The squeal disappeared when we applied a water mist. I wondered if the glue was melting and causing problems but I have no evidence of it on the bit. Nor do I see evidence of burning that you get with a slow feed rate. The chip size was fairly large being about 10 mils long and 5 mils wide and about 2 mils thick.
I ordered some straight flute and spiral cutters for friday delivery, I'll find out then.
I should post some pics of the router, it's not fancy but it's under $10k.
ernie
-------------------- Ernie Balch Balch Signs 1045 Raymond Rd Malta, NY 518-885-9899 Posts: 405 | From: Malta, NY | Registered: Jan 2003
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Dianne, Victor, and anyone who responded to this post... I'm curious what CNC you're using. Please advise. (Bob, I know you have a new Warthog).
Thanks.
Fran
-------------------- Fran Maholland Pro Sign NJ Posts: 169 | From: Voorhees, New Jersey | Registered: Feb 2003
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Ernie, I can't add anything to the above except to say, be sure to tell us what you find.
The quarter inch bits are really rugged compared to the 1/8 inch ones you used to use. But if the work grabs on the bit, like a piece of scrap abruptly pinching the tool path, it will pop the bit right off.
I said before we didn't break bits on MDO. That is incorrect. The vacuum table doesn't hold wood down as tightly as other materials, because the wood tends not to be flat. The centers of letters sometimes want to move and can create a jam that will break a bit.
posted
I am cutting with a ShopBot which is pushed by ArtCam, Insignia.
The one product I suggest for any CNC is a Vortec Tube to cool the bits. There is no reason for misting with one of these. The company we bought ours from is "Arizona Vortex" for about $200. it's small and comes with a magnet base to attach close to the bit. It will throw blistering cold air on a bit, saving it's life and sharpness.
j
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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Joe, I just heard about this type of cooling a few weeks ago but didn't know a brand or what they were called the guy that told me about it says it works great.
-------------------- Dennis Raap Raap Signs Posts: 839 | From: Coopersville, MI | Registered: Feb 2003
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The flexible plastic tube that is attached to the Vortex tube, which deliver the cold air to the bit, will from time to time get into the bit.
No problem. Your can replace the end portion. It looks permanently attached but isn't. I bought two new 12" plastic tubes last week for $10 each. They came with four tips each.
j
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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You know, Ernie, I contact "Joe" from Practical CNC a number of times and he doesn't seem to return e-mails or calls. Hmmmm... Anyway, I did speak with him once a while ago and he said that some of the nuances(spell)for 3D and signmakers weren't quite in place yet with the P-CNC. I wonder if things have changed and if they are now working the sign market more. Soon to get a CNC machine once all my research is completed and the budget makes it affordable. IS the P-CNC a fairly rugged machine? Any comparison with the Shopbot? Please advise... and thanks for all the other info associated with this post.
Fran
-------------------- Fran Maholland Pro Sign NJ Posts: 169 | From: Voorhees, New Jersey | Registered: Feb 2003
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When I bought my router in Dec, Joe said his business had jumped from 1 cnc table per week to 5. He only has a few people and they seem to be busy. I had a few complaints and they were taken care of quickly.
Joe said he had been approached by a big sign making software company to build a private label router. Last I knew he was designing a full commercial style router.
I bought the system from Joe knowing that it was only a starting point. But he sells them cheaper than I can buy the parts and the engineering is already done.
The flashcut software is fantastic. I would use it on any project.
ernie
-------------------- Ernie Balch Balch Signs 1045 Raymond Rd Malta, NY 518-885-9899 Posts: 405 | From: Malta, NY | Registered: Jan 2003
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