Machsupport Forum
General CNC Chat => Show"N"Tell ( What you have made with your CNC machine.) => Topic started by: Jammerm on April 11, 2014, 11:06:49 AM
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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I had thought of that but didn't know if it would work. I'll give it a try, thanks.
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Have you tried the Corian yet? It will engrave with extremely fine detail. Should be perfect for a pattern.
John Champlain
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I was thinking of trying it today. Wife has a big Honey-Do list for me so it may have to wait... until about December! :)
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I tried the Corian with some new bits I got. It works great, cuts like I imagine Ivory would. Letters look great and the little weeds in between the letters are pretty tough to get out, I'll have to get the Dremal out and finish the clean up.
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I'll have to get the Dremal out and finish the clean up .............
........ and then post some nice pictures ! ! ! ;D
Happy it worked out well for ya ! Anxious to see it.
Kind regards,
Russ
:)
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I tried the Corian with some new bits I got. It works great, cuts like I imagine Ivory would. Letters look great and the little weeds in between the letters are pretty tough to get out, I'll have to get the Dremal out and finish the clean up.
I see that I am not alone, in using a Dremel for the detail work!
How much did the Corian set you back? (and what size pieces for the price?)
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Jammer,
I'm not sure what you need to clean with the Dremel, but I use a watery paste of BonAmi pot scrubbing powder and a toothbrush to clean my Corian engravings.
John Champlain
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http://www.ebay.com/itm/151283964107?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
It was $2.75 a piece for a 6 by 12" piece. Looks like he has sold out for now.
I have some engraving tools and have used them to start cleaning up the letters. I'm just afraid of slipping with the Dremal.
I'll get some pictures, I actually did a different plaque that is more detailed.
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Ok, I finished them up and did a couple Ford logos. I meant to put something in for scale but the ford logos are 36 and 41mm high on the ovals.
(http://i183.photobucket.com/albums/x310/Jammer_55/CNC%20Build/003.jpg)
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What I was going to clean up with the dermal was little areas in between the letters that the 1/16" bit could not fit into. Is there another way to clean out these areas with the code?
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Hey ..... they look really nice !
I especially like the way you negated any issues with "top billing" too.
Can never be too careful.
Good job, thanks for posting !
Regards,
Russ
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What I was going to clean up with the dermal was little areas in between the letters that the 1/16" bit could not fit into. Is there another way to clean out these areas with the code?
I've seen some CAM's that have "Rest" machining. This allows you to change to a smaller bit and then it only cuts what the larger cutter was unable to.
You still have a rad, but a bit smaller. (bit dependent)
By hand with carving tools is the only way I know of to get a sharp inside corner.
Very tedious and time consuming.
Other solutions, I'm sure.
Russ
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Hard to tell, are you using a ball mill ? or flat ?
What CAM ?
You could load a smaller cutter and just profile the features with your cam ?
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The letters are cut with a 20 degree tapered bit and the clean up is a flat bit. It's .0500" deep. The angle is for metal casting. This person plans on casting these in Brass. I took longer than expected so he may have to hurry or do it after the wedding. He asked they be cut both ways. The strange thing is they didn't cut the same. The letters on the second one are a little thinner and it was harder to clean up. I haven't seen any smaller bits and broke one of these by dropping it on the concrete. :(
I'm using the free program, F-engrave, it works great for larger items but if I'm going to do much of this small stuff, I'll have to invest in a better CAM program.
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What I was going to clean up with the dermal was little areas in between the letters that the 1/16" bit could not fit into. Is there another way to clean out these areas with the code?
I work with MeshCAM Art, for my 3D stuff. It does a great job, since it creates a tool path for the roughing cut, as well as the finishing cut. (I usually use a 1/4" bit for the rough, and a 1/8" bit for the finishing cut). You can actually "LIE" to MeshCAM about the diameter of a tool (I tell it the .125" bit is a 0.94" bit). This forces the software to create a more detailed tool path for the finishing cut. However, since most of what I carve is recycled tractor-trailer flooring, (Oak) it still sometimes requires some touch-up work by hand using a Dremel tool. As for areas that are too small for the tooling to reach into, this is best handled at the artwork design phase. Simply space the letters further apart, to accommodate the tool diameter. I use Corel Draw in designing my artwork. And what I typically do, is to draw a circle .125" diameter, and drag it around the drawing using it as a "measuring device" to check the spacing of my artwork. If it won't fit between letters in the design phase, then the bit won't fit between them when you are carving. I have found it to be a great time-saver, for checking the artwork prior to tool path creation.
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There were only about a dozen little bits to cut out. These plaques are only about 4" wide, I think the letters were 30 pt size. Too small for raised letters. I've got some other ones to do but they aren't so detailed. I did a bronze casting yesterday of a small plaque I did for another fellow. I'll try to get some pictures on.
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Here's the other little plaque, about 4" long. It's for a friend that has restored a set of Howe Scales and needed the name plate for it. I'll let him decide to paint the background or just add some patina. The original was painted with a red background, I believe.
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Looks like they turned out great!
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The fellow I sent the finished plaque to cast it in brass. The metal may have been a little hot, hard to get the temp right in a home foundry. He's going to try it again when he gets a day off. The best thing to do with this type of casting is to sand or machine off the top of the letters and heart to give a smooth surface. Add patina to the background.
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Beautiful!