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Small project not going well
« on: April 11, 2014, 11:06:49 AM »
I'm working on some small patterns and having a lot of trouble with the wood chipping out. My spindle is running at 30,000 rpm and I'm using new carbide bits. I've tried some MDF, Basswood, and something else I think was elm, it was terrible. Any suggestions? I'm using F-Engrave and the letters are very small. I guess I need a Laser.
What kind of wood carves best? Should I coat it with some kind of sealer?
This is like a coaster, about 4" diameter.

Offline Tweakie.CNC

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Re: Small project not going well
« Reply #1 on: April 12, 2014, 02:52:38 AM »
Hi Jammer,

That lettering is indeed pretty small to expect not to chip-out.
I don't know if you have tried it but the composite Bamboo seems to take fine engraving quite well but requires sealing before colour filling to prevent paint bleed.

Laser would be good, particularly now that the 4 Watt or so diode lasers are available at reasonable prices but it would still make for expensive coasters  :)

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Small project not going well
« Reply #2 on: April 24, 2014, 12:21:00 AM »
I'm working on some small patterns and having a lot of trouble with the wood chipping out. My spindle is running at 30,000 rpm and I'm using new carbide bits. I've tried some MDF, Basswood, and something else I think was elm, it was terrible. Any suggestions? I'm using F-Engrave and the letters are very small. I guess I need a Laser.
What kind of wood carves best? Should I coat it with some kind of sealer?
This is like a coaster, about 4" diameter.
A couple of points here, Oak or similar hard woods make the best engraving materials. Also, even though you may have high speed on the spindle RPM, if you are also attempting a high-speed feed rate, it will yield poor results. The tool needs time to do it's thing (and eat away the material to be removed) if you are trying to drive it at a high feed rate, then the "Contact Time" of the cutter to the material is reduced, and can be part of the problem.
So, try: 1-hard wood material 2-slower feed rate and see if it yields an improvement.

Re: Small project not going well
« Reply #3 on: April 24, 2014, 10:58:45 AM »
Thanks Adprinter, I have been using softer woods on this. I'll see if I can find a piece of Oak. I've got all kinds of wood I picked up at an exotic wood place but, most of them are small pieces. They were in the scrap bin and I only paid a buck or so a pound for them.
I have slowed the feed down to a crawl, I think it made it worse on the soft woods. It seemed to grab a lot more.
I just got some Corian from the Bay and I have ordered a new spindle. My cheap router does have some wobble to it and it's hard to set the bit so it spins true.
I did a large sign the other day and it all worked fine. Sign came out great. It's just the small fine detail stuff I'm having a problem with. My homebuilt machine may not be solid enough to try things like this.

Offline ger21

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Re: Small project not going well
« Reply #4 on: April 24, 2014, 12:16:40 PM »
I think you'd be better off with a closed grain wood like maple rather than oak. Oak will tend to splinter more due to its open grain.
Another option is to seal the surface with shellac or some other clear finish before cutting. This will hold the wood fibers together and result in cleaner cuts.
It's also very important to always use very sharp bits.
Gerry

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Re: Small project not going well
« Reply #5 on: April 25, 2014, 10:57:23 PM »
Are you making all the cuts accross the grain first and then with the grain too minimize chipping. The other thing to try is doing all the cutting in the wood end gain. Good luck.
Re: Small project not going well
« Reply #6 on: April 26, 2014, 05:58:15 PM »
These are to be used for a pattern to cast in Brass. I tried some Polypropylene but it just melted. I have some soft Maple and the Corian came the other day. I also got some new bits and a new spindle is on the way.
The program I'm using just follows the outline of the letters and pretty much goes whatever way it feels like.   
Re: Small project not going well
« Reply #7 on: April 26, 2014, 06:31:49 PM »
On a similar project, I did the engraving/milling to about twice the depth required, then faced the blank off with a very sharp fly cutter, then a final flat sanding left all of the edges/corners very sharp and clean.
Might work for you as well.
Russ
Re: Small project not going well
« Reply #8 on: April 26, 2014, 08:12:02 PM »
I had thought of that but didn't know if it would work. I'll give it a try, thanks.
Re: Small project not going well
« Reply #9 on: April 29, 2014, 08:17:12 AM »
Have you tried the Corian yet?  It will engrave with extremely fine detail.  Should be perfect for a pattern.
John Champlain