First cut slower then set in TC for clean edge in wood

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DomCa
Posts: 18
Joined: Tue Nov 05, 2019 9:00 pm

First cut slower then set in TC for clean edge in wood

Postby DomCa » Wed Nov 27, 2019 10:15 am

Hi all,

I wonder if there is a kind of dress-up that allows perfoming a "first cut" in wood for providing a clean edge.

What I imagine is a minimal depth cut, maybe 1mm, with slow speed and high RPMs to provide a clean cut edge on the top of the wood. The high volume material removal may then be done with quicker feed rates.

In my case I woul like to cut the first cut with max. 500mm/min and then continue with 1000mm/min or more.

I am fairly new to FreeCAD, but I think I could simply create two jobs for this. The first job would use a TC that has a lower feed rate and would start on the top of the workpiece and end at 1mm. The second job would use a TC that has the high feed rate and would start at the hight where the first job ended and go through the workpiece.

However, a dress-up would realy speed up things, no?

In addition, the last/lowest cut (if I cut through the whole piece of wood) could also be such a slow cut to provide a nice edge on the other side of the workpiece, too.

I had this idea, when I cut the top for my router work bench. It took quite long! I know that as a hobbyist I could simply wait, but I think such dress-ups would be a cool feature to have.

Thanks
DomCa
herbk
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Location: Windsbach, Bavarya (Germany)

Re: First cut slower then set in TC for clean edge in wood

Postby herbk » Wed Nov 27, 2019 12:58 pm

Hi DomCa,
DomCa wrote:
Wed Nov 27, 2019 10:15 am
I am fairly new to FreeCAD, but I think I could simply create two jobs for this. The first job would use a TC that has a lower feed rate and would start on the top of the workpiece and end at 1mm. The second job would use a TC that has the high feed rate and would start at the hight where the first job ended and go through the workpiece.
Thats the possible way atm... It's not much work if you copy the whole job and just change the parameters. With a dressup you would not be much faster in my mind, because you have also to set the parametersyou want.

Espacialy for woodworking it would be better if the feedrates are part of an operation, not part of the job. And, because it`s a need if you want work in a professional way with wood, you need different feedrates depending to the direction of the woods grain alignment.
Gruß Herbert
DomCa
Posts: 18
Joined: Tue Nov 05, 2019 9:00 pm

Re: First cut slower then set in TC for clean edge in wood

Postby DomCa » Wed Nov 27, 2019 1:38 pm

Hi herbk,

thanks for your reply. I never tried copying the job, good info!

Do you know if it is possible to create an operation with specific feedrates or to create an operation with direction specific feed rates? If not, I think this would be a great improvement of the PATH tools in FreeCAD. As alternative, I suppose I could create different tool controllers with different feed rates.

If the alignment of the wood is along one of the main axis of my CNC, I could probably use different horizontal and vertical feed rates in the tool controller to provide different feedrates along the wood alignment in a single operation, correct?

Best regards,
DomCa
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sliptonic
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Joined: Tue Oct 25, 2011 10:46 pm

Re: First cut slower then set in TC for clean edge in wood

Postby sliptonic » Wed Nov 27, 2019 3:02 pm

DomCa wrote:
Wed Nov 27, 2019 10:15 am


What I imagine is a minimal depth cut, maybe 1mm, with slow speed and high RPMs to provide a clean cut edge on the top of the wood. The high volume material removal may then be done with quicker feed rates.

In my case I woul like to cut the first cut with max. 500mm/min and then continue with 1000mm/min or more.
What principle would cause a cleaner edge on the top surface? A slow feed rate with a high RPM would mean the cutter is rubbing on the material most of the time rather than cutting it. This will cause the cutter (and the material) to heat up.

I know cutting wood and getting a nice surface finish is tricky but I've also found that it has much more to do with direction of travel relative to the wood grain than does depth of cut or feed rate.
chrisb
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Re: First cut slower then set in TC for clean edge in wood

Postby chrisb » Wed Nov 27, 2019 3:26 pm

You can use the same job if you clone the tool and use one of them with different speed.
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Russ4262
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Joined: Sat Jun 30, 2018 3:22 pm

Re: First cut slower then set in TC for clean edge in wood

Postby Russ4262 » Thu Nov 28, 2019 9:49 pm

My $0.02 is to use a different bit for the first cut. Using a down-cut bit will provide a cleaner cut through the surface than the more common up-cut bits. Up-cut bits are much better for material removal, and thus more prevalent. The up-cut wants to force the wood upward, causing splintering and tearing at the surface, but the down-cut doesn't have this problem to the same severity when used for the first cut through the top surface.

This info is based upon what I have read, not on personal experience.

Russ