3d carvings in red cedar cutting speeds

[ajf]

I'm doing a series of red cedar stairway panels for a client largely based on Vector Arts wildlife series models. The panels average size is 4'x2' by 1 1/4" thick and max. depth of the carvings are around 3/4". I have PRSstandard with a Porter Cable router. When I create the roughing and finishing tool paths for these carvings using the default parameters for 1/4" and 1/8" round nose end mills that Aspire provided I noticed my total cutting time ends up to be close to 20 hrs. per panel. I would like to speed up this time if I can and was wondering if anyone has any experience with red cedar and what type of speeds and depths they were able to use and get a satisfactory final finish done in a reasonable amount of time. Clear red cedar is priced like gold here so I don't particularly want to do the trail and error method of finding out how much I can push this machine. I guess I should also ask if you have any particular bits you find work well in red cedar.

Thanks

[dlcw]

I've done several signs here for companies here using WRC (located in northwest US, cedar is priced like oak back east).

Here's my experience: Use a 1/2" ballnose to do your rough pass. Do your rough pass cross grain as WRC splits out pretty easy and running with the grain will cause long chunks to split out. I feed at 4-5ips with spindle speed at 9k RPM. I use a 40% stepover to really hog out a lot of material quickly. If you are starting out with a small carving then rough pass with a 1/4" ballnose (same settings for 1/2"). It looks pretty rough when this pass is done.

Finishing pass I go with the grain at 4-5ips with spindle at 8k RPM with a 1/8" ballnose bit with 6% stepover if there is a lot of fine detail otherwise I use a 1/4" ballnose with a 10% stepover. If I'm doing a REALLY detailed carving then I will make a first finishing pass cross grain with a 1/8" ballnose with 10-13% stepover and a second finishing pass with a 1/8" ballnose with the grain at 6% stepover. Virtually no sanding required and the detail is superb.

It boils down to how much detail you want in the carvings. The more detail, the smaller the bit and the lower your stepover rate.

WRC is soft and driving a 1/8" ballnose through fast doesn't normally result in a broken bit (knock on wood, haven't broken one yet in WRC).

[ajf]

Thanks for the reply, especially the tip about going cross grain on the rough cut. Could you tell me what depth of cut per pass you are using for the various size of bits with the settings you mentioned. Also what has been the best bit for you to use in WRC.

[dlcw]

I use bits from Centurian for most of my carving work. As far as depth of cut per pass with a 1/2" bit I'll cut .375"; 1/4" I'll cut .25"; 1/8" bit I'll cut .125".

Be careful and don't try these depths, feeds and speeds with harder woods, you'll most likely break the bit.

[gc3]

I'm doing a series of red cedar stairway panels for a client largely based on Vector Arts wildlife series models. The panels average size is 4'x2' by 1 1/4" thick and max. depth of the carvings are around 3/4". I have PRSstandard with a Porter Cable router. When I create the roughing and finishing tool paths for these carvings using the default parameters for 1/4" and 1/8" round nose end mills that Aspire provided I noticed my total cutting time ends up to be close to 20 hrs. per panel. I would like to speed up this time if I can and was wondering if anyone has any experience with red cedar and what type of speeds and depths they were able to use and get a satisfactory final finish done in a reasonable amount of time. Clear red cedar is priced like gold here so I don't particularly want to do the trail and error method of finding out how much I can push this machine. I guess I should also ask if you have any particular bits you find work well in red cedar.

Thanks


At 20 hrs for that size and depth with the detail of that panel...20 hrs per panel is not a bad run time. Check your speeds, ramp rates, 3d threshold and adjust as needed. As I am still a rookie at 3D carving I found Bill's turtorial on ramp rates a MUST read.

Don is correct with the rough across grain.

I did some door panels 22X78x.625 on a older pr machine and the rough/finish run time was 11 hrs. .5 endmill rough 80% step, .25 ballnose 10% step.

[dlcw]

20 hours is not bad at all. I've attached a picture of a table I did that was on the CNC for 25 hours and then I attacked it with hand chisels for another 10 hours.

[bleeth]

Beautifully done Don. Are the feature animals inlaid or carefully stained/painted? All who are recent to their cnc for this purpose need to understand that fine definition 2.5D cnc work is time consuming, unless you compare it to the time it takes to go to town on your blank with dremels, knives, and gouges!!

[dlcw]

Dave,

I am honored with the compliment on the table, especially coming from you. :D

The animals were brought more to life using gel stains. I'd apply a coat, let it dry and then buff it out ready for the next coat. Each animal has about 6 or 7 coats of different tones of gel stain to achieve the look I wanted.

Like Dave said, just because you have a CNC to do initial carving, it is just another tool in your toolbox to achieve your end goal. The big advantage of the CNC is that when it is working on a project, you can be doing something else. Kinda like an employee how never complains, shows up late to work or asks to leave early. Other then cabinet parts, the CNC has never "finished" a project for me. It is just one step in the overall process. Don't look to the CNC to do the finishing work for you. It just ain't gonna happen.

[ajf]

After reading as much as I could find on the site about 3d carving and the bits to use, I decided to order some spare ball nose bits before I started cutting. I didn't think it would be a problem as many people had recommend certain suppliers. So I go to order online and I find out that I can not complete my order because it appears I can not give them a valid billing /shipping address because it seems the Yukon is not part of Canada. In another case it is consider an international order because it isn't in North America so a minimum order of several $100 is required before they will accept an order.
So my question is to Canadian owners of ShopBots is there a good supplier in Canada were I can order some ball nose bits.

[ajf]

I'm doing a series of red cedar stairway panels for a client largely based on Vector Arts wildlife series models. The panels average size is 4'x2' by 1 1/4" thick and max. depth of the carvings are around 3/4". I have PRSstandard with a Porter Cable router.
These panels cut OK using the default feed and plunge rates (.83 and .33 ips) that Aspire provides for the final tool path cut using 1/8" ball nose cutter in a raster pattern. But based on what I've been reading in forums I should be able to go faster. However when I increase these rates everything seems fine until it comes to a rapid elevation change in the z axis then the x and z axis motors start making a horrible sound and if it is a large panel that I'm cutting the motors get almost too hot to touch. I've tried changing the ramp settings as indicated in the forums but that didn't seem to help. I'm wondering if there is something else I should be looking at.

[cowboy1296]

@DON. I have never used the extra pass at 90 degrees but have calculated it. Surely the calculations are wrong because it does double the time in cutting, according to the software. seems to me like there would be a lot of air cutting going on, but since i have not done it whats the deal with the calculations. are they correct or am i dong something wrong.