I need a very slow set epoxy

[Roger Feeley]

I’m going to make an end grain cutting board for a wedding gift. It will involve a couple of hundred little blocks of contrasting wood. I would like to do the whole board in one gluing session so I need at least an hour before clamping and I think that’s pushing my luck. Two hours would be fantastic.

my alternative would be to glue up three or four rows at a time and then glue the sub assemblies together.

Does anyone know of a very slow cure epoxy?

[Bryan Lisowski]

If the board is actually going to be used, I would not use epoxy. I would use titebond extend or something similar.

[Andrew Hughes]

I would like to suggest gluing up in sections using tite bond 3. You can thin it to give more open and gets smaller glue lines.
The epoxy I use is system 3 . It’s expensive and found it to be so thin that I get a darkness around joints from the epoxy seeping in the wood. I’ve also had large batches harden quickly because the air temperature was too high.
Epoxy is great for some stuff but definitely not the cure all especially for visible glue lines.
Good Luck

[Steve Gojevic]

I use a lot of epoxies at work for various prototype builds.

3M makes DP-190, which has a pot life of 90 minutes. It comes in gray or translucent color. the gray is much higher viscosity than the translucent.

Also, most epoxies get harder as you approach the end of the pot life, so I would say the actual usable pot life is just over an hour.

Steve

[Kevin Jenness]

Some vendors have slow hardeners, like West System 206. Any epoxy mix can be slowed by working in a cool environment, spreading the mix out in a thin layer in a tray, putting the tray on ice and doing a series of small batches through the glueup process. Because the thickening process is progressive you can usually get your pieces coated and clamped while the adhesive is still fluid enough to flow under pressure. Once spread into a thin film the setup slows compared to the mix in a pot or tray. Gluing up in stages is a valid option.

The wicking effect Andrew describes can be an issue, so do a sample before committing to epoxy.

Be aware that epoxy bonds best to sanded or sawn surfaces. West System recommends sanding @ 80#.

[Mike Henderson]

The West System Epoxy has a slow hardener. You can extend the pot time by putting the epoxy in a container and then sitting that container into a pan of ice.

Mike

[Oops, I see Kevin said the same thing.]

[johnny means]

Even West "fast" epoxy gives you plenty of open time. But, I doubt the speed of your adhesive is the big hurdle here. Clamping up a bunch of little blocks is going to be a beast. Typically, these things are glued up into substructures first. This also allows for flattening between glue ups for tighter seams.

[Curt Putnam]

Does not epoxy weaken with heat? Hopefully the board will not go in the dishwasher but it will probably get into hot dishwater. What about Unibond 800 or DAP Weldwood? Just asking.

[Bruce Wrenn]

I’m going to make an end grain cutting board for a wedding gift. It will involve a couple of hundred little blocks of contrasting wood. I would like to do the whole board in one gluing session so I need at least an hour before clamping and I think that’s pushing my luck. Two hours would be fantastic.

my alternative would be to glue up three or four rows at a time and then glue the sub assemblies together.

Does anyone know of a very slow cure epoxy?

First watch a couple you tubes on making end grain cutting boards. They aren't made up from individual blocks, but laminated strips, which are cross cut to yield rows of already glued up blocks. For glue, use TiteBond type 3, instead of epoxy. Use a router sled to flatten tops and bottoms before sanding ( a lot!)

[Prashun Patel]

I don’t know how you will be able to glue up individual blocks perfectly; every single block in each row has to be exactly the same size. I agree that they are usually more easily done by gluing strips, cross cutting, rearranging, then regluing.

Either way, I would do them a couple rows at a time. Easier to keep things flat.

[Roger Feeley]

Thanks to all. I think trying to do the whole thing in one session is just too much. I’ll work out a way to divide and conquer.

the happy couple are both engineers and very computer literate. I plan to convert their names and wedding date to a precursor to ASCII called Baudot which was used for stock tickers and teletype type machines back when 110 baud was fast. I’ll use contrasting wood for mark and space bits. At a glance it should be a nice random pattern.

I’ve done this sort of thing before. The cutting board we have was a sort of inside joke. I took a rubbing of the ceramic tile backsplash at our old house and recreated it block for block in an end grain cutting board. You wouldn’t see it unless you know it’s there. Now we are in a different house so it’s just a nice random pattern of three colors of wood.

[Mike Henderson]

Thanks to all. I think trying to do the whole thing in one session is just too much. I’ll work out a way to divide and conquer.

the happy couple are both engineers and very computer literate. I plan to convert their names and wedding date to a precursor to ASCII called Baudot which was used for stock tickers and teletype type machines back when 110 baud was fast. I’ll use contrasting wood for mark and space bits. At a glance it should be a nice random pattern.

I’ve done this sort of thing before. The cutting board we have was a sort of inside joke. I took a rubbing of the ceramic tile backsplash at our old house and recreated it block for block in an end grain cutting board. You wouldn’t see it unless you know it’s there. Now we are in a different house so it’s just a nice random pattern of three colors of wood.

Are you going to make the code look like strips of teletype paper tape? That would be cool and would be the way it would be read.

Mike

[Thomas McCurnin]

+1 for West Systems. Hide glue also has a long open time. Regular white glue has an edge over Titebond.

I think making a project specific gluing jig and wedges (or veneer press hardware) would help significantly to reduce glue up time and increase accuracy.

[Frank Pratt]

+1 for West Systems. Hide glue also has a long open time. Regular white glue has an edge over Titebond.

I think making a project specific gluing jig and wedges (or veneer press hardware) would help significantly to reduce glue up time and increase accuracy.

But "regular white glue" has almost no moisture resistance & the board will begin to fall apart in a hurry.

[andy bessette]

There is no possible way to rationalize taking TWO hours to assemble/glue-up a cutting board, no matter how elaborate the pattern. It is a simple matter to have all the different pieces organized beforehand, ready to assemble in their natural order, so that assembly can be done in an efficient manner.

Use WEST Epoxy Extra Slow Hardener if necessary, though the need for that seems highly doubtful. Also the use of WEST's Special Hardener seems more appropriate, as it is lowest in toxicity and therefore used in constructing water tanks.

[Richard Coers]

You can slow down any epoxy by spreading it out thinly in a tub and then set that in a pie pan filled with cold water.

[Roger Feeley]

That would be fun but it would be too easy. I don’t want it to be too obvious. My objective is to produce something that will look fairly random unless you know the secret. I love adding a little twist. If you want ordinary, go to IKEA.

I started my programming career right at the end of the teletype era. My first job was with Commodity News Service in Kansas City. They had recently converted from teletypes to a Tandem. When they gave me a tour, they showed me a back room with some teletypes just in case that new-dangled computer didn’t work.

[John K Jordan]

Are you going to make the code look like strips of teletype paper tape? That would be cool and would be the way it would be read.

Mike

Ok, anyone else here actually used a teletype at home? In the '70s I built my first computer (6800) and for $800 I bought a refurbished ASR 33 teletype with a tape punch and reader. It could read or write 10 characters per second. The thing was noisy so I kept it in my living room closet. Used it to load and save software and for a keyboard and printer until things evolved where I could build a CRT terminal and we could buy floppy disk drives.

At one time the only way to buy software was on paper tape OR type in the hex code printed on paper sheets, one byte at a time. My first drives used 1.2meg 8" floppies which changed everything. I could buy one floppy disk for $10. Orders of magnitude better than the paper tape! All this time the "internet" was through a telephone handset set on an audio coupler - my data rate was 10 characters/second.

Somewhere I still have a bunch of punched paper tape I've saved for history.

JKJ

[Brice Rogers]

I suspect that Tite-bond is a better adhesive.

But you asked about a slow-cure epoxy. You'll need to experiment, but I've thinned epoxy with acetone so that it would soak in to the pores and cracks. It substantially slowed down the cure time. In my case it was several hours. But the amount of slow down depends on your dilution level. So, experiment first.

[Brice Rogers]

Yes, I had a model 14 teletype. It printed out on 1/2" tape that had adhesive on the back. It was probably what Western Union used to glue up telegrams. I got it for free. I hooked it up to a home made circuit that would decode audio teletype code. I am a ham radio operator. It actually worked surprisingly well. I printed out stuff from other ham radio operators as well as from a variety of unknown-source commercial broadcasts.

I used paper tape with a "Friden Flexo-writer" to print out annual Christmas letters and also custom resumes. Plus I used paper tapes to load data to "burn" an Eprom.

I also remember using punch cards for data entry on a CDC 6600 super computer (probably the power of a cell phone today). I enjoyed all the noise that it made.

[andy bessette]

...I've thinned epoxy with acetone so that it would soak in to the pores and cracks. It substantially slowed down the cure time. In my case it was several hours. But the amount of slow down depends on your dilution level. So, experiment first.

Very bad advice and tech. Never add anything to epoxy that is not expressly recommended by the formulator.

[Mike Henderson]

Ok, anyone else here actually used a teletype at home? In the '70s I built my first computer (6800) and for $800 I bought a refurbished ASR 33 teletype with a tape punch and reader. It could read or write 10 characters per second. The thing was noisy so I kept it in my living room closet. Used it to load and save software and for a keyboard and printer until things evolved where I could build a CRT terminal and we could buy floppy disk drives.

At one time the only way to buy software was on paper tape OR type in the hex code printed on paper sheets, one byte at a time. My first drives used 1.2meg 8" floppies which changed everything. I could buy one floppy disk for $10. Orders of magnitude better than the paper tape! All this time the "internet" was through a telephone handset set on an audio coupler - my data rate was 10 characters/second.

Somewhere I still have a bunch of punched paper tape I've saved for history.

JKJ

I didn't have one at home, but when I received my commission in the Signal Corps in 1969, I was then sent to Signal Officer's Basic Course. One thing we learned (and saw) was how the military handled message "switching". They had a room with a bunch of teletypes which were point-to-point. When a message came in, it was punched to paper tape. Someone read the address of the message and then physically took that paper tape to another machine to pass the message on. It might go to the final recipient, or it might go to another "switching center" where it would be passed along again.

It was like a modern computer router, but with people doing the routing.

Mike

[David Sochar]

I think "Fall apart in a hurry" is a near-wild overstatement. Try it. The joint will have to dissolve from the outside edges in, and could fail after several/many dunkings.

I would not advise using white glue, but it was/is a viable glue, even in high moisture situations.

[Frank Pratt]

I think "Fall apart in a hurry" is a near-wild overstatement. Try it. The joint will have to dissolve from the outside edges in, and could fail after several/many dunkings.

I would not advise using white glue, but it was/is a viable glue, even in high moisture situations.

No, it is not an overstatement at all. I've been there. If the cutting board sets in a puddle, or someone unknowingly puts it in a sink of water for a few minutes, it will be the beginning of the end for that board. The glue in the outer edges of the joints will first fail quickly, leaving a small gap that moisture will readily wick into, further eroding the glue.

[Frank Pratt]

I suspect that Tite-bond is a better adhesive.

But you asked about a slow-cure epoxy. You'll need to experiment, but I've thinned epoxy with acetone so that it would soak in to the pores and cracks. It substantially slowed down the cure time. In my case it was several hours. But the amount of slow down depends on your dilution level. So, experiment first.

Thinning epoxy has serious implications for the strength of the joint. Check with the manufacturer, but even using solvents that they recommend will weaken the epoxy.

[Steve Demuth]

Yup. The upgrade from a KSR 33 at 110 baud a suitcase luggable 330 baud thermal printer was mind expanding back in the day. Writing and editing code on a teletype was just agonizingly slow. The HP 2100s we used for device controllers and time sharing took about 40 linear feet of paper tape to start. You'd key in the bootstrap loader using the front panel switches (probably 30 or 40 or so 16 bit 'words'), then stick the roll of tape in the reader and it'd shoot through at about 10 fps. That'd get you enough code to start the 5 Mb disk drive that was roughly the size of a big microwave, and be able to "talk" to the machine through a teletype.

When we retired the teletypes, I liberated 3 boxes of the newsprint paper that they used, and stuffed them in our attic. My home schooled kids never lacked for paper to draw on, or do whatever. We used the last about the time the youngest was outgrowing that kind of "art."

My first boss in the computer business used to give tours to school groups. We had a battery powered, hand held little spinner that we used to re-roll the boot tape after starting the machines. When a smart aleck kid would ask what the spinner was for, he would say that's how you "cranked" the computer into life if it was balky, and stick the business end of the spinner into a recess on the machine to demonstrate. We were in a farm community, so a lot of the kids were familiar with hand cranking a balky Farmall M or H, so more than one bought the story.

[Roger Feeley]

As I wrote, Commodity News had only recently retired teletypes when I started. But I got to hear stories of teletype chaff wars in the newsroom and other war stories. CNS distributed a number of news wires over what they claimed was the biggest uninterrupted copper network in the world, ATT 7073. Some stories would be of interest to multiple wires so the paper tape would be fed through one teletype machine first. The operator would coil the tap into sort of a figure 8 and throw it across the room to the operator of another wire and so on. I would have loved to see video of that. I’m told that it was well ordered chaos.

I don’t miss the rat race, but I do miss the rats.

[andy bessette]

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