Tape + CA question

[Carl Beckett]

600 is a lot of cats Brian.

You have it working. But would be great to figure out how to run with less labor.

Wondering about Michaels method of leaving a thin skin. Would not require a vacuum, just make it a little thicker. (absolute vacuum can only get ~15 psi, so fundamentally limited but maybe leave enough to support the entire set at once). Then flipping the entire panel and running through a drum sander to bring them down and remove the skin all at once. Which also produces a sanded part. (as long as they stayed down.... cats make me nervous, dogs would be inclined to behave better)

(a quick search found a post where they left a thin skin then flipped, finished sanded with a hand sander and the parts fell out...)

[Michael Burnside]

Thanks for the reminder Carl, I spaced the fact that you can either use a drum/hand sander to take the skin off or use a razor blade/oscillating tool and clean the edges by sanding or flush trim bit. Because the skin is so thin it quickly disappears.

[Steven O Smith]

One thing I was surprised by when I started using blue tape/CA was that on larger pieces, the corners need to be weighted or they pull up a little bit. This only matters if the depth of cut is important, and it's a small amount, maybe 1/32".

I'm also not seeing the point of using medium CA and accelerator. I just use the thin stuff.

Steve

[Brian Tymchak]

600 is a lot of cats Brian.

50 dozen, a dozen each per gift. That was the goal. Didn't seem like that big of a challenge at first. But life intervened and held me up for a while.

You have it working. But would be great to figure out how to run with less labor.

Indeed. That idea of leaving a skin is interesting. Appreciate Michaels and your input on that. I might try that this afternoon. Along those lines, I just got a mop sanding head set up yesterday. First time I've worked with one. Got me thinking that I might be able to go back to thin tabs and use a thin 120 grit mop to knock the tabs off and then a fluffy 180 to smooth edges. The 240 I set up yesterday works but is slower than I expected.

[Jim Becker]

I'm also not seeing the point of using medium CA and accelerator. I just use the thin stuff.

The medium (or thick) gives you a little more time to "get 'er down" and there's less risk of the glue flowing where you don't want it to go. Thin will work for sure, however.

[John TenEyck]

One thing I was surprised by when I started using blue tape/CA was that on larger pieces, the corners need to be weighted or they pull up a little bit. This only matters if the depth of cut is important, and it's a small amount, maybe 1/32".

I'm also not seeing the point of using medium CA and accelerator. I just use the thin stuff.

Steve

The corners are pulling up because the wood is bowing. It can happen if the blank was prepped but not carved until sometime later, and it can happen during the carve if you remove enough wood, or if the RH changes while you are carving. Large blanks need to be clamped at the corners, and sometimes at mid span, to keep it flat. There's no solution I'm aware of for blanks that want to heave up in the middle, maybe an incredibly good vacuum system?

John

[Steven O Smith]

This was a couple of pieces of 12mm baltic birch, shellac on both sides.

[Jerome Stanek]

what size bit are you using.

[John TenEyck]

I've had plenty of pieces of Baltic birch that weren't dead flat.

John

[Brian Tymchak]

After seeing all the responses from everyone (Thanks!) I ran a job using masking tape and I could find no real difference in any aspect between masking tape and blue tape.

I have to recant my claim.

After using beige masking tape for a couple days, and then going back to blue tape when I ran out of the beige, I decided that the blue is better in 2 aspects. It does release easier from cut parts, and since it's blue, it's a lot easier to see on light wood, which, to me is no trivial thing.

I'll probably stick with blue as the cost savings of beige is probably offset, at least in some part, with the extra time to clean it off the 0arts.

[Brian Tymchak]

Now that the holiday pressure is off, I took some time last week to experiment with alternatives to using blue tape+ CA to cut these cats. Playing off Michaels post about leaving a thin skin, I wondered if I could use thin tabs to hold the parts together. As it turns out this works great! Using tabs 0.05" thick, the parts hold in place for the last pass and are thin enough that the tabs trim off completely with the round over pass at the router table.

I also tried using hot glue to hold the hardwood to a secondary spoilboard, and then clamping that to my primary spoilboiard. Made sure that there was enough material left at the edge to act as a frame so the tabs held solid. Again, it worked great. So, I've completely eliminated blue tape and CA from my process, saving a bunch of time and expense.

As a bonus, I also hit on a better solution of the cats position relative to one another in the design, such that I upped the yield about 30%. So with the higher yield and elimination of the cost of tape+CA, I think I can produce 75 dozen for about the same cost as the 50 dozen this year.

Kinda fun refining the process to get better results.

[Carl Beckett]

Was wondering if you ever tried that Brian - definitely on my list to try. I did some small repeat projects where I left tabs on end grain. They tended to burn when I sanded them off. Was thinking I could have left a skin since I broke the corners anyway with a 1/16 roundover. Exactly as you confirm.

.050 is fairly substantial - am thinking that should hold reasonable well.

How did you break them free after machining?

[John TenEyck]

Tabs and leaving a few thousands uncut both eliminate the necessity of using tape and CA glue, but both come with their own compromise. The problem with tabs is that the workpiece ends up having little vertical lines on the side where the bit stopped moving forward so that the Z axis can move up whatever the height is before moving forward, and then repeats where it steps back down. This even happens with 3D tabs for me. Those lines are very difficult to clean up in hard wood. And then there's still the matter of having to remove the tab.

Leaving a few thousandths on the bottom is the better option for me, but you have to be careful not to damage the bottom edge of the workpiece when removing that "flashing" afterwards.

Blue tape and CA glue is still the best option for me most of the time when I can't use clamps, dowels, or screws.

John

[Michael Burnside]

For pieces I can clamp, I rarely have a problem with tabs. When I’m designing I only add them on long grain edges. Usually 0.010 tall and 1-2” long. I also almost always use the same 1/4 end mill that perfectly matches my flush trim bit. You cant even see it when I’m done.

When I can’t clamp a top side, I use the skin technique Brian talked about with my vacuum table. Or I just go no clamps at all if it’s all down cut or surfacing and vbit work. There I just use dogs and my track

[Brian Tymchak]

Was wondering if you ever tried that Brian - definitely on my list to try. I did some small repeat projects where I left tabs on end grain. They tended to burn when I sanded them off. Was thinking I could have left a skin since I broke the corners anyway with a 1/16 roundover. Exactly as you confirm.

.050 is fairly substantial - am thinking that should hold reasonable well.

How did you break them free after machining?

Hey Carl, I just used a 1/4" chisel to pop them out after flipping the carved board over. I did learn the hard way to be a little careful with the chisel after leaving a few marks on the piece from the edges of the chisel. Just a very light tap with a mallet will cut the tab.