V Bit carving

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Re: V Bit carving

Postby cconway » Mon Oct 08, 2018 2:42 pm

Thanks Scott. I find it interesting that a lot of you have coated the surface first, but clearly see where that could have benefits. I'm looking forward to running some test cuts in the next couple of days to see what happens. I'll keep you posted. Thanks again to everyone.
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Re: V Bit carving

Postby martin54 » Mon Oct 08, 2018 10:35 pm

cconway wrote:Thanks Scott. I find it interesting that a lot of you have coated the surface first, but clearly see where that could have benefits. I'm looking forward to running some test cuts in the next couple of days to see what happens. I'll keep you posted. Thanks again to everyone.


Your not just coating the surface, the sanding sealer soaks into the wood & helps to reinforce the fibres, that is one reason why I said if you were doing a deep carving you may have to apply another coat after you have cut to a certain depth :lol: :lol:
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Re: V Bit carving

Postby cconway » Sat Oct 13, 2018 1:55 am

I ran a few test cuts the other day. The cut was the same as my original post. First one was at 12,000 rpm, .25 pass depth and .3 ips. Although the cut is better than my original there is clearly still a lot of teat out and chatter. The next one was at 16,000 rpm, .25 pass depth and .3 ips. Overall this looks to be an improvement. It seems the increase in spindle speed had a positive impact, but it still has issues. The last cut is with the same settings, but I sprayed it with sanding sealer first. No difference in the overall quality of cut, but it did sound like it was running smoother. Based on this first round of tests I'm leaning toward leaving the spindle speed at 16,000 and the the feed at .3 ips, but decreasing the pass depth to .20 or .15 to see what I get. I would appreciate your opinions on this. Am I on the right track or off in lala land.

Thanks,

Charlie
Attachments
cut 1.jpg
Cut 1- 12,000 rpm, .25 pass depth, .3 ips
cut 2.jpg
Cut 2 - 16,000 rpm, .25 pass depth, .3 ips
cut 3.jpg
Cut 3- 16,000 rpm, .25 pass depth, .3 ips, sprayed sanding sealer
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Re: V Bit carving

Postby cconway » Sat Oct 13, 2018 2:53 am

Hopefully this post is not showing up twice. I thought I posted it earlier. I did some test cuts which were with the same material and letters as the original. In cut 1 I think there is a clear improvement over my original post, but still chatter and tear out. In cut 2 increasing the spindle speed to 16,000 seemed to have a positive impact although there are still issues. In cut 3 the sanding sealer did not seem to make a significant difference in the quality of the cut, but it did sound like it was running smoother. Based on these finds my thought is to leave the spindle speed at 16,000 and the feed at .3 ips but decrease the pass depth to .20 or .15 to see what the impact is. I would appreciate hearing your thoughts on this. Am I on the right path here or off the crazy train.

Thanks!

Charlie
Attachments
cut 1.jpg
Cut 1 - 12,000 rpm, .25 pass depth, .3 ips
cut 2.jpg
Cut 2 - 16,000 rpm, .25 pass depth, .3 ips
cut 3.jpg
Cut 3 - 16,000 rpm, .25 pass depth, .3 ips, sanding sealer
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Re: V Bit carving

Postby martin54 » Sat Oct 13, 2018 11:46 am

Have you asked this question on the shark forum? Since this is machine related you might get better answers as the people on the forum will mostly be running shark machines :lol: :lol:

For me it is just a case of experimenting until I find out what works best for me, different combinations of speed, feed & DOC settings, refine things as I go which is pretty much what you are doing. I would certainly try a shallower DOC with a range of different speed & feed settings.
Have you tried using a different V bit of the same angle? I have had brand new bits that were blunt, not often but it has happened even with good quality bits :lol: :lol:

http://www.cncsharktalk.com/index.php
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Re: V Bit carving

Postby ger21 » Sat Oct 13, 2018 12:00 pm

Sealing the wood will not prevent tearout inside of the V Carving. It will only help at the transition from the flat surface to the V Carve.

To prevent tearout in a V Carve, you need a very sharp bit, lower feedrate, or higher rpm.
Sharp bit will help the most. You might also want to do a light finish pass.
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Re: V Bit carving

Postby scottp55 » Sat Oct 13, 2018 4:55 pm

Lightening up the pass cuts to at least .15" may give the best results...You're close!
But like Gerry said a Good, and Sharp bit is key as much or more than feeds and speeds.
What bit are you using?
Don't know if this would help, but I was in the habit of cleaning my router bits with a brass brush using what is now BladeCote after every use before I put it away(LIKE knowing ALL my bits are clean when I grab them quick on a long day)...and then continued the habit when I started CNC work. I used to think Bosch bits were top of the line before CNC, and found they were mid level.
Keep experimenting until you get the cut quality you want...THEN you can start gradually increasing Fees AND speeds together until the blend of quality vs time makes sense to you.
Every machine and wood is different....LISTEN and FEEL the machine while cutting, and you'll soon get a feel for your machine.
As long as the bit stays cool to the touch after a cut, and you're producing chips(even if they're small)....You're good to go regardless of chip load charts.
For my stuff the defaults were always to aggressive for top quality cuts.
I virtually ALWAYS run toolpaths twice Like Michael, as it saves so much hand work afterwards, and I'm lazy and would rather the machine spent time than me. Besides I have other work to do :)

Like Gerry and Martin say, atop coat of finish really only helps tearout on the material surface. Gerry's comment is similar to what I'd do on problematic material, Except I Zero as usual, then Nudge my Zero up what I'm seeing the tearout is(.01-.02"). Cut/apply finish/lower my Z zero down to original height, then cut again. Finicky, but I use oil finishes, and finish accentuates any tiny flaw.

You're getting better! :D
scott
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Re: V Bit carving

Postby ctbjdm » Sat Oct 13, 2018 7:40 pm

No major suggestions on the cutting parameters, but GO HUSKIES!
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Re: V Bit carving

Postby cconway » Sat Oct 13, 2018 11:33 pm

Thanks for the feedback everyone. Scott the bit I am making these cuts with is the Amana RC-1142. Its a 90 deg 1.5 in dia.
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Re: V Bit carving

Postby scottp55 » Sun Oct 14, 2018 12:52 am

Zip experience with that bit:(
When I started adding bits. and looking at posts**** some were swearing by them, some simply swearing at them.
As I was just a hardwood newbie..I never got into them.
That info should get some more specific responses for you though:)
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Re: V Bit carving

Postby martin54 » Sun Oct 14, 2018 4:55 pm

cconway wrote:Thanks for the feedback everyone. Scott the bit I am making these cuts with is the Amana RC-1142. Its a 90 deg 1.5 in dia.


I know some people swear by Amana can be difficult to get in the UK so I have no experience of them but as I said earlier even a quality bit can have issues so worth checking with a new bit of the same brand or a different brand doesn't really matter :lol: :lol: :lol:
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