cutting out small parts

This forum is for general discussion regarding VCarve Pro
redwood
Vectric Wizard
Posts: 301
Joined: Wed Apr 13, 2016 3:38 am
Model of CNC Machine: Axiom Pro6
Location: No. Calif.

cutting out small parts

Post by redwood »

I have some toy vehicle designs from MakeCNC that I'm hoping to make for a charity to give away at XMAS. I'm cutting them out of 1/4" Baltic birch plywood. I'm wondering if I need tabs for these little parts. I've actually cut out 2 vehicles already. I had setup tabs, but they didn't hold or I cut through them. None of the parts seemed the worse for wear, despite being completely cut out and a couple popped out of their places.
I'm using a 1/16" downcut endmill. To give you a idea of size, the preview is a 2' x 2' square and the assembled vehicle is around 5" long.

My question is? Was I lucky that nothing went flying or was destroyed. Or is safe to just cut them out without tabs.
farmtruck.jpg
farmtruck.jpg
Mark
Pioneer, CA

garylmast
Vectric Wizard
Posts: 1580
Joined: Fri Oct 23, 2009 4:03 pm
Location: Sandy, Utah

Re: cutting out small parts

Post by garylmast »

I would use tabs. If you are using a dust collector, it will also save from sucking up the small part.

Gary

redwood
Vectric Wizard
Posts: 301
Joined: Wed Apr 13, 2016 3:38 am
Model of CNC Machine: Axiom Pro6
Location: No. Calif.

Re: cutting out small parts

Post by redwood »

I normally use a dust collector, but I wouldn't for this. Not using tabs would be a huge time saver in not having to cut them all out, as well as not having to place the tabs. There are approx. 33 pieces in that car.

With 1/16" endmill, I'm taking 5 passes to cut them out. I have no idea what happened to the original tabs in my first try. They were setup as .1" thick x .375" wide.
Mark
Pioneer, CA

User avatar
highpockets
Vectric Wizard
Posts: 3667
Joined: Tue Jan 06, 2015 4:04 pm
Model of CNC Machine: PDJ Pilot Pro

Re: cutting out small parts

Post by highpockets »

How are you holding the plywood down?

I'd use painters tape and ca glue. Make sure to have the tape covering at least a portion of each part.
John
Maker of Chips

User avatar
Adrian
Vectric Archimage
Posts: 14544
Joined: Thu Nov 23, 2006 2:19 pm
Model of CNC Machine: ShopBot PRS Alpha 96x48
Location: Surrey, UK

Re: cutting out small parts

Post by Adrian »

Where are you setting the z zero and how accurate is the thickness of the material?

4DThinker
Vectric Wizard
Posts: 1701
Joined: Sun Sep 23, 2012 12:14 pm
Model of CNC Machine: CNC Shark Pro, Probotix Meteor 25" x 50"

Re: cutting out small parts

Post by 4DThinker »

Your tabs likely disappeared because the depth of cut was a bit more than the actual plywood thickness. Rarely is 1/4" bb plywood actually 1/4" thick. When I do small part like this I'll pocket away small inner waste areas so I don't have to worry about making/dealing with tabs for those. I'll leave out tabs on large pieces if I'm watching the CNC as they cut and can usually reach in and hold the piece in place on the last pass. Otherwise I measure the true thickness of any material I'm using with a digital caliper. Set that in Vcarve. I make tiny tabs for tiny pieces usually .05" by 1/4" long, trying to only do them parallel with the grain on the bottom layer of the plywood. 1/4" BB plywood is often 6mm or .236" thick.

4D

redwood
Vectric Wizard
Posts: 301
Joined: Wed Apr 13, 2016 3:38 am
Model of CNC Machine: Axiom Pro6
Location: No. Calif.

Re: cutting out small parts

Post by redwood »

I did measure the plywood with calipers, it was .196". I held down the 2'x2' ply with 8 holdowns. There was a very, very slight bow of the plywood in the center, which I didn't realize until the parts were cut out and I could see the ever slight movement when I pushed down on the plywood.

I actually ran the profile toolpath at .196", with the tabs. The tabs were present, but it didn't appear to cut all the way through the ply. I released one side of the holdowns and lifted the ply and confirmed it did not cut all the way through. So I added .005" to my cut and all but 2 pieces cut all the way through, but also eliminated my tabs. That may have been the result of starting my profile cut at .196" and cutting .005" deeper.

My point is that everything turned out fine and saved me a ton of time cutting all those tabs. I'm hoping to make 16 of these little vehicles, so we are looking at approx. 500+ parts. My hope is/was, that using such a small endmill on very tiny parts allowed me to get away without any tabs. Not one piece was damaged. Was I just extremely lucky?
Mark
Pioneer, CA

User avatar
Adrian
Vectric Archimage
Posts: 14544
Joined: Thu Nov 23, 2006 2:19 pm
Model of CNC Machine: ShopBot PRS Alpha 96x48
Location: Surrey, UK

Re: cutting out small parts

Post by Adrian »

All depends on the material, bit type, cut direction and finishing point. Many items I cut I don't use tabs or any method to hold down the cut part and it works fine with large and small pieces. Same thing in a plastic rather than wood or with a different cut direction or finishing point and it's flying halfway across the room before it's finished.

User avatar
scottp55
Vectric Wizard
Posts: 4713
Joined: Thu May 09, 2013 11:30 am
Model of CNC Machine: ShopbotDesktop 5.5"Z/spindle/VCP11.5
Location: Kennebunkport, Maine, US

Re: cutting out small parts

Post by scottp55 »

I'd recommend John's method, but never personally used it (but just bought materials to try it).
After trial and error we came up with a method remarkably Like Russ's;
viewtopic.php?f=27&t=26319&start=30 (end of page 2- beginning page 3)

BUT didn't have any vinyl transfer tape, so used Duck brand "No Residue Duct Tape" and Ace Hardware 1.88" double sided carpet tape in pic because on the other sizes the paper sticks awful.
Used this method on waxed HDO for thousands of buttons and keyfobs down to 1"D and cutting out with Drillman1's .25" 60 degree vbit and whiteside .5" .25"Radius point cutting roundover which has a LOT more force than yours.
Most were .2" thick.

Closest thing to your project I've personally done with no problems was some "Twig" butterfly joint inlays(.22" thick) for an Ebony piece that developed a crack on Mom's XMas present...so I just used the same set up as buttons, and it worked a charm. Pics look like it's not a clean cut, but I cut a little deep and that was sawdust mixed with carpet tape residue and came of with rubbing my finger across it.

Been thinking of trying CA between two pieces of the No Residue Duck Tape, but haven't needed it yet.
IF I had tried masking tape/CA personally......?

IF! Your material were totally flat on the spoilboard, then I might try just letting the Downcut pack the kerf with sawdust and hold it in place like a fair amount of people do after experimenting. AND if going .005" deeper than material for the cut out, I'd make the last pass .01" to leave just a skin to be cut on the last pass.
That takes a perfectly flat spoilboard, and I'd reference to the spoilboard.

Just thought I'd mention it.
scott

Oh, Maybe nest a lot closer together, and possibly group the individual types of parts for all the trucks together for tighter nesting and less sheets?
I hate screws, but they're better than having the sheet bowing. After nesting and toolpathing, make a circle larger than diameter of screw head, and with actual cut showing in blue in 2D view, place circles in areas that are safe.
Attachments
CHAD 5.jpg
DRILLMAN 1 .0625 DOWN MOM MALE INLAY 2.jpg
6.5.17 SASSAFRASS MOM'S TWIG SMALL.jpg
6.5.17 SASSAFRASS MOM'S TWIG SMALL RELEASED.jpg
DRILLMAN 1 .0625 DOWN MOM MALE INLAY.jpg
Bloodwood Bonnies cut 11.11.15.jpg
I've learned my lesson well. You can't please everyone,so you have to please yourself
R.N.

User avatar
scottp55
Vectric Wizard
Posts: 4713
Joined: Thu May 09, 2013 11:30 am
Model of CNC Machine: ShopbotDesktop 5.5"Z/spindle/VCP11.5
Location: Kennebunkport, Maine, US

Re: cutting out small parts

Post by scottp55 »

Dug for the uncropped pic of actual tapes that worked best.
Attachments
CHAD 1.jpg
I've learned my lesson well. You can't please everyone,so you have to please yourself
R.N.

ger21
Vectric Wizard
Posts: 1592
Joined: Sun Sep 16, 2007 2:59 pm
Model of CNC Machine: Custom DIY
Location: Lake St Clair, MI, USA
Contact:

Re: cutting out small parts

Post by ger21 »

A 1/16" bit will have very low cutting forces, so plain old double faced tape would be the easiest method. My preference is golf club grip tape, which is similar to plain old tan masking tape, but two sided. It's very sticky, but easy to get off. Much, much better than carpet tape imo.

And your .196 BB is 5mm.
Gerry - http://www.thecncwoodworker.com

User avatar
scottp55
Vectric Wizard
Posts: 4713
Joined: Thu May 09, 2013 11:30 am
Model of CNC Machine: ShopbotDesktop 5.5"Z/spindle/VCP11.5
Location: Kennebunkport, Maine, US

Re: cutting out small parts

Post by scottp55 »

I agree with Gerry, that using carpet tape by itself is a sticky, time consuming mess...but used like Russ and I do as a sandwich between two layers of no residue tape like his vinyl transfer tape, or my Non-Residue tape is great:)
Gives just enough thickness so if something is off a bit, you don't cut into your carrier board.
The tack on that Duck tape is probably more than you need(about 2/3 of regular Duck Tape and 50% of Gorilla duct tape), but releases extremely clean even after the stated "90 days".
Cut some Bloodwood for John from a scrap that had been on the HDO for a year and released clean:).
I've learned my lesson well. You can't please everyone,so you have to please yourself
R.N.

User avatar
SteveNelson46
Vectric Wizard
Posts: 2282
Joined: Wed Jan 04, 2012 2:43 pm
Model of CNC Machine: Camaster Stinger 1
Location: Tucson, Az.

Re: cutting out small parts

Post by SteveNelson46 »

Turners tape works pretty good too. Woodcraft has a couple of different strengths. Also there's the double sided tape that has the red pull tape and labeled as "permanent" (Home Depot). Nothing is permanent but that stuff really sticks.
Steve

kstrauss
Vectric Craftsman
Posts: 276
Joined: Mon Apr 29, 2013 3:37 am
Model of CNC Machine: Tormach PCNC770
Location: Cobourg, ON, Canada

Re: cutting out small parts

Post by kstrauss »

I use https://www.amazon.com/gp/product/B000QDL9GK/ when cutting tiny parts from thin plastics such as Delrin. It isn't cheap but is much thinner than most carpet tape and is cleanly removable.

KeithW
Vectric Craftsman
Posts: 118
Joined: Sun Jun 08, 2014 3:13 am
Model of CNC Machine: Probotix Meteor, Aspire 8.014
Location: Red Deer, AB

Re: cutting out small parts

Post by KeithW »

I use green masking tape (2" if project allows) and CA glue. It is worth trying!

Clean spoil board, (no dust etc), put tape down and rub it down

Clean back of board, put on tape and rub it down well also.

Run a small bead of CA glue on the tape on the spoil board, and spray the back of the other piece with accelerator, and then put it down on the other tape.

Be careful not to get any glue on the spoil board OR YOU WILL be stuck down!

It doesn't take every much to hold. When finished just pry it up; it's only like masking tape coming off of a board.

Beats any other hod down, especially for cutting of small parts.

Post Reply