Work holding

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CEG
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Work holding

Post by CEG »

I have been using VCarve to cut out small parts from .032 inch or .9mm half hard sheet brass. Sheet sizes 180 x 75mm.
Does anyone have a pet method for holding thin material? I have had the super glue tape method fail on me more than once. Using screws directly into 18mm MDF has been quite successful, although screw placement in a nest of parts can be a pain.

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sharkcutup
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Re: Work holding

Post by sharkcutup »

Nest size of how many 180 x 75mm sheets?

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TReischl
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Re: Work holding

Post by TReischl »

I do not use the tape super glue technique. That is just me.

Couple of things. Tape. All tape is not created equal. I like to use tape to glue up box corners. I found that the blue painters tape has a nasty habit of slowing letting go. But when I thought about it, made sense. Since it is painters tape it should come off easily. I use a green tape (do not ask me for the item number, I have no clue). It is quite a bit stickier than the blue stuff but still releases clean.

MDF, you mentioned it. Tape has never held well for me on MDF, especially if it has been surfaced removed the dense outer layer. I am sure it works for other folks. But what you could is make up a board with formica to create a non porous surface that tape loves. I needed some a couple of years ago. Headed to the big box store and found a piece that had been damaged. Got it for a huge discount.
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rtibbs
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Re: Work holding

Post by rtibbs »

As ted says "Nothing sticks to MDF very well". I'm using the tape/cyanoacrylate method for cutting small pinion gears.
Two things I have found to help are: (1) I put a couple of coats of sanding sealer on my spoilboard.
(2) I'm using Scotch Rough Surface extra strength painters tape #2060 (Green)

On real small pinion gears put a small pin into my spoilboard and slide the gear blank onto the pin. That along with the tape method works for me.
I think I'll try the packing tape as Ted suggested.

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Re: Work holding

Post by gregk »

CEG wrote:
Sun Mar 08, 2020 3:23 pm
I have been using VCarve to cut out small parts from .032 inch or .9mm half hard sheet brass. Sheet sizes 180 x 75mm.
Does anyone have a pet method for holding thin material? I have had the super glue tape method fail on me more than once. Using screws directly into 18mm MDF has been quite successful, although screw placement in a nest of parts can be a pain.
To make screw placement easier with nesting, you could try the following. Draw a rectangle with the size of your sheet, then add appropriately sized circles in place where you would like to place screws and group everything. When nesting select that group last and tick 'Last vector is nest boundary' option.

I hope this helps,

Greg K

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Re: Work holding

Post by ger21 »

Super glue directly to MDF, and use acetone to release.
Gerry - http://www.thecncwoodworker.com

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TReischl
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Re: Work holding

Post by TReischl »

rtibbs2018 wrote:
Sun Mar 08, 2020 10:49 pm
As ted says "Nothing sticks to MDF very well". I'm using the tape/cyanoacrylate method for cutting small pinion gears.
Two things I have found to help are: (1) I put a couple of coats of sanding sealer on my spoilboard.
(2) I'm using Scotch Rough Surface extra strength painters tape #2060 (Green)

On real small pinion gears put a small pin into my spoilboard and slide the gear blank onto the pin. That along with the tape method works for me.
I think I'll try the packing tape as Ted suggested.
RT, actually I was not suggesting packing tape. But I have seen videos of guys using it. I ordered some 3M green tape on the amazon site.

It also occurs to me that there is "knock off" blue painters tape. I sorta try to stick (pun intended) with 3M stuff because they are the masters of all things sticky.
"If you see a good fight, get in it." Dr. Vernon Johns

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rtibbs
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Re: Work holding

Post by rtibbs »

[/quote]

RT, actually I was not suggesting packing tape. But I have seen videos of guys using it. I ordered some 3M green tape on the amazon site.


[/quote]

Oops, How bout as Ted mentioned.

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TReischl
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Re: Work holding

Post by TReischl »

RT, I like your idea of putting a small pin inside the pinion gear to take up the side thrust of the cutter.

Something that might help also is to use a straight cutter instead of one with a helix. On a standard helix cutter it will try to lift the material up as it cuts.
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Re: Work holding

Post by dgw@telus.net »

The blue tape (3M) and super glue technique works surprisingly well. I use it for pretty much everything. If your MDF spoilboard is fairly clean, if will stick well. Once you try it, you will never go back!

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Re: Work holding

Post by martin54 »

As usual Ted's advice is sound, Not CNC related but I use a wide range of different tapes all designed for different purposes. I buy a branded tape that I am confident will do the job. If I have an aplication I am unsure of I phone my tape supplier & get their advice.
If you bought a branded tape such as 3m or scotch you are less likely to have failures, I use a brand called Tesa tape & buy from a company who specialise in tapes.
A seperate board with a surface that is more receptive to tape would also help. the sheet size you have mentioned isn't very big so a small offcut would be enough, screw that to the spoilboard & then use the tape method. If this is repeat work then you could make your screw on board a proper fixture that fitted to the same part of your table each time & then set up a work offset so you didn't have to set your x y zero each time you used it :lol: :lol:

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rtibbs
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Re: Work holding

Post by rtibbs »

TReischl wrote:
Mon Mar 09, 2020 2:26 pm
RT, I like your idea of putting a small pin inside the pinion gear to take up the side thrust of the cutter.

Something that might help also is to use a straight cutter instead of one with a helix. On a standard helix cutter it will try to lift the material up as it cuts.
I added the pin on all my pinions as with only CA/tape holding I've had a couple of "Flying gears" :o

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Re: Work holding

Post by tomgardiner »

You might want to consider five minute epoxy. After machining you can release the glue with a hot air gun or torch. Acetone will remove the rest.
The problem with tape is the adhesive isn't very heat resistant. Unless you are misting the brass temperature may rise to the point of tape failure.

CEG
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Re: Work holding

Post by CEG »

Thanks for all the great replies. Sounds as it is a more common
problem than I realized.
Cheers, Chris

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rtibbs
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Re: Work holding

Post by rtibbs »

Had to cut some pinion gears this morning so I thought I'd give the "Packing Tape" a try as I appears to adhere to the spoilboard better than my green rough surface painters tape.
While it may adhere to the spoilboard better I found that the CA doesn't adhere to the packing tape :(
Thankfully I was using wooden dowel "Pins" set into my spoilboard.
The green tape/CA with pins works best. :mrgreen:
Pinions.jpg
All's well in "Gear land"

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