[mwmkravchenko]

The shortest way to answer that question Mike is that I have used every type of contact cement you have named and a couple that John has mentioned. I never use the stuff on wood veneer. It fails as I mentioned.

Longer answer is that on commercial work that will be replaced before failure yes it gets used from time to time as it is a much faster method of applying flat veneer or curved veneers to panels. But as for longevity there are better methods. Iron on yellow glue method is one of the easiest and most forgiving. If John had used veneer tape to setup his book match and border he probably could have used the iron on method. You have to tape both sides when you need to play with setup a bit more than usual. Veneer tape is very thin and not a problem when under the veneer.

Mark

 

[johnnyfamous]

The contact debate continues. You make many valuable common sense points Mark, But I think given the type of wood i am using and the small amount of veneer, contact will last for many more years than 10. perhaps on a large panel with many seams, I would suspect a commercial enviroment would be more demanding on veneers than residential and perhaps you might see the fail rates that you state in a resturant but probably not in my constant temprature, low humidity house. I have used allot of the waterborne contact in commercial/instatutional settings and its strength compaired to solvent is poor at best. That being said, your not wrong.:surrender:

I dont understand though how a NON convertable coating (yellow glue) will have a stronger bond strength after it has dried and then heat is applied to reactivate (which in theory is not possible with non convertable coatings) than a solvent based contact? I would think that the bond strength would be similar to water born contacts. ???? It seems very easy to work with mind you.

I appreciate your experience here, thanks. I want this to last many many years, so I am not apposed to trying a better method, I dont have any veneer to waste on this though so there is no room for mistakes. Why do you need to spray the veneer with water when using the urethane glue? and do you spray it on the glue side or the finish side?

 

[mwmkravchenko]

Hi John

I'm just yakking about contact. It is an opinion. You have enough knowledge to make an informed decision. That is all I'm trying to aid. The failure rate is exactly what you describe. Heavy use and abuse. But that's what cabinets get up against in commercial use.

Urethane adhesives chemical reaction requires water as a catalyst. It is not really a true catalyst as in the sense of car paint or such. But without free water moisture the stuff takes forever to set. One side of a lamination is all that is required to be moistened.

With what you said about having only so much veneer. You definitely have the skills to do a good job with the contact cement. And I agree completely that the water borne stuff is much better than the solvent borne.

I have no specs on the iron on yellow glue method. What the heat is doing is creating a phase change. Like hot melt adhesive. Heat it up and it will re-harden together. Heat it up apply pressure and you should at least in theory get a better bond than contact cement. I have to put this stuff to the test on some samples and I will get back to you on that one. I have a whole bunch of prototype boxes I have to finish to keep some people happy! Maybe I can slip in some time on that job and get some actual comparisons.

I saw the coolest idea for a cheap vacuum pump last night. A guy used a pool air pump and hooked it up on the vacuum side of the pump. He measured 120 grams / cm^2 vacuum pressure. I get 1.7 lbs/ inch^2 or 1.7 * 144 = 245 lbs/ ft^2 A bit better than the weight idea. And about all you could generate with the clamp system I have used before.

Just for kicks and giggles I should take some pics of the next vacuum bag job. I have an actual pump I bought from princess auto about 20 years ago. But it can be done on your air compressor if you have one. Once you set up for that you will never go back to any other method. Bags can be made from 10mil polyethylene and tuck tape or even duct tape. And a double roll over a skinny board with some spring clamps will self seal the open end of the bag.

Just causing trouble and raising dust!

Sorry to post common sense thought John. You are not just a finisher I think. You probably have quite a bit of cabinet experience as well.

Mark

 

[johnnyfamous]

Hi John



Urethane adhesives chemical reaction requires water as a catalyst. It is not really a true catalyst as in the sense of car paint or such. But without free water moisture the stuff takes forever to set. One side of a lamination is all that is required to be moistened.

With what you said about having only so much veneer. You definitely have the skills to do a good job with the contact cement. And I agree completely that the water borne stuff is much better than the solvent borne.



I saw the coolest idea for a cheap vacuum pump last night. A guy used a pool air pump and hooked it up on the vacuum side of the pump. He measured 120 grams / cm^2 vacuum pressure. I get 1.7 lbs/ inch^2 or 1.7 * 144 = 245 lbs/ ft^2 A bit better than the weight idea. And about all you could generate with the clamp system I have used before.

Just for kicks and giggles I should take some pics of the next vacuum bag job. I have an actual pump I bought from princess auto about 20 years ago. But it can be done on your air compressor if you have one. Once you set up for that you will never go back to any other method. Bags can be made from 10mil polyethylene and tuck tape or even duct tape. And a double roll over a skinny board with some spring clamps will self seal the open end of the bag.


Sorry to post common sense thought John. You are not just a finisher I think. You probably have quite a bit of cabinet experience as well.

Mark

Hey Mark, So i tried a test of the polyurethane, the results were much better than the yellow glue, In fact was very impressed! I will give it a try on the top sides, i suspect i will have favorable results:sn:

Think we had our wires crossed, I think the adhesion of the solvent products are much stronger than the water born contacts not vise versa as you state,, but i suppose its irrelevant anyways..

I would appreciate it if you could post some pictures of your vacume press system. My hesitation has been cost, having no veneer to make mistakes, and not wanting to wreck my compressor....Probably a little lazy to try something new as well:unbelievable:

I took a good look around princess auto yesterday. And they have a great fitting supply. I have a good understanding of what is needed but have a question, do you let the pump run continuos for two hours or would it not be wise to use a automatic pressure shut of to cycle the pump on and off as required? I did not see one there. I would hate to put that load on my compressor for an extended time.:help:

 

[johnnyfamous]

started work on the inlay, tricky to get the squares to line up at all four corners. I used a half inch mortise bit in my trimmer and set up guides, measured about 20 times before i started to route.

Had to hand chissel the outer corners, I will try the polyurethane glue to set, hopefully i get to it today.


Hey is there a spell check on here??? my spellinz @#$% .:nerd:

 

[mwmkravchenko]

First the complements. Beautiful. The inlay will really set things off nicely. I'm happy the test worked out well for the polyurethane glue. I should have told you about that stuff first. Brain damage from to much contact cement when I was young and invincible. At least that's my excuse!

I took a good look around princess auto yesterday. And they have a great fitting supply. I have a good understanding of what is needed but have a question, do you let the pump run continous for two hours or would it not be wise to use a automatic pressure shut of to cycle the pump on and off as required? I did not see one there. I would hate to put that load on my compressor for an extended time.

Oh I have to do this... Ever hear of a valve? It shuts things off and stops stuff from moving in and out of pipes. :rofl2:

I know I'm bad. But this is going to be one of those Doooh times.

You run the compressor given it is an oil lubricated compressor. It takes about 3 to 5 minutes depending on how big your bag is at the time and how much air you have squeezed out when closing it up. You have a ball valve in line and when you are happy that every thing has squeezed down to the point where it is actually tight you close the valve and shut off the compressor. Will it hold a vacuum forever? Probably not but it does give some time for your compressor to rest. Your gonna be watching it like a hawk for sure. Plus it's really cool to think that you are clamping with nothing but the pressure of 100 miles of air above you. Then your little brain will come up with all kinds of other things you can glue with type of a setup. You have to watch out. If you have already done some checking you'll find that the platen everything rests on should be cross hatched about 3/16" every so often to allow a path for the air to escape. I have snapped a couple of these when I'm pressing curved objects. On a flat you can break it but you have to draw quite a heavy vacuum to pull it off. Remember I use a dedicated vacuum pump. It is a rotary type compressor. But your air compressor will work quite well. If you are really sneaky you run a tank in line and shut off the system between the tank and the compressor and you have reserve vacuum just like you can have reserve compressed air when using a compressed air gun. But I digress. You have to cycle things every once and a while. You will get leaks from fittings just like with compressed air. SO my recommendation is to get a tractor tire metal valve stem and cement this to your bag close the end say about a foot back from the open end of the bag. You can also finangle some other fittings but you want as braod an ara as you can to glue the exit from the bag to the compressor or it will break loose quite quickly. I used shoe goo a couple of times and I have used silly cone as well. Flextra is another tenacious caulking. But here it is only available at Rona not Home Despot. Solder on a valve to the tire stem before so that there is no chance for a leak. If you have a fitting that will allow threading don't forget the teflon tape. If you figure out a different way to tap the bag make sure that the valve is as close to the bag as possible. And use a ball valve. I used a washer and seat type and it has always leaked. I'm going to change it over to a ball valve myself.

Pics of my setup will come in the latter part of January. My shop is being enormously revamped these past couple of weeks I'm trying to turn it from a setup and work shop to a well setup work shop and the vacuum pump and bag setup is in the shop attic. Not much doing up there. My setup is not al that pretty anyway. But it does work. I use it quite a bit when I have alot of flat P-lam to do. You never get lamination failure when you use yellow glue and it cycles in and out of the bag as high as you can stack it up in about 1/2 hour when you are doing doors and drawer ronts for comercial work. I had one client try to tell me that glue method would not hold. So I gave him a sample and offered the job for free if he could cause a glue failure. He paid for the job and was a happy camper to boot. But there are pics on the net that tell the story properly.

As for contact cement I think I'll stick with water based. It is better for my health as there are much less VOC's in the water borne stuff. I think it has come quite a ways from twenty years ago when we used to laugh at the stuff and say nothing holds better than solvent borne. The one I found to hold the best was formica brand from Richilieu. But the best of both is not even in the same league as the polyurethane you are planning on using.

Mark

 

[johnnyfamous]

Oh I have to do this... Ever hear of a valve? It shuts things off and stops stuff from moving in and out of pipes. :rofl2:

I know I'm bad. But this is going to be one of those Doooh times.

Ha,Ha,,,not quite what i meant mark,:rofl: I was reffering to one of these "automatic devices"

http://www.veneersupplies.com/product_info.php?products_id=58



Glad to see that there not required, how long do you hold the press for and are you just using yellow PVA glue or still the urethane? Do you use a wire mesh of some kind in the bag or just the hatched platens?

 

[mwmkravchenko]

Hi John

I clamp Yellow PVA for about 1/2 hour as it sets easily in that amount of time. Urethane you have to read the bottle as they are different for each. My bottles say 3 hrs at I'm guessing room temperature. I have bottles of Elmer's polyurethane in the shop right now.

The trick is to not use any more glue than you need. I roll it on with a small foam roller. The kind you can get at Home Despot for painting. They are cheap and they usually come with a little tray the first time you buy them. It puts just a thin film on the pieces and it works well and sets fast.

Thanks for the link to the vacuum switch. I have been looking for a cheap vacuum controller for years but they were always crazy amounts of money. Around $200 last time I really looked about 10 years ago. This one is cheap even though I will have to setup a relay for my pump as it is quite a beast. I bought it. When you are working in a shop not having to pay close attention to something if you don't have to is worth the money!

I'll let you know how it performs if you'd like. But you would have to replace your pressure switch on your compressor to make it work. If you have an old compressor then great but if you need your compressor for regular duty then it is not of much use. There are surplus sites on the net where you can find cheap vacuum pumps from time to time. Vacuum can be used for all kinds of clamping and work holding where there is sometimes no other way to accomplish it. Tons of possibilities.

I have used hatched platen exclusively. Come on a cabinet shop always has scrap pieces kicking around right? I use the scrap to make a platen. Sometimes they last a while.

I have not used Urethane in a large layup as of yet. I have used a lot of urethane on projects for quite a few years but I have not done any large amount of vacuum pressing for at least 6 or 7 years. Clientele shift was one thing that changed my usage pattern. Divorce 13 years ago where my ex sold my complete shop for pennies kind of screwed up things for a while to! That's when I did some carpentry for a couple of years and then Graphics design for 2 years. Then back to good old cabinet making.

Mark

 

[johnnyfamous]

finally finished the inlay.was not that much work or as hard as i thought, just finicky. The urethane glue worked a charm!

 

[mwmkravchenko]

Looking great!
Like your application of the interior clamping. Those boards look like they are really putting on the pressure. Can't wait until you have some finish on it to really show off the contrast in the color.

Mark

 

[mwmkravchenko]

Hi John

I have been looking through the www.joewoodworker.com sight that explains all about vacuum presses. Wow I learned a couple of things to. Great sight. I used a timer switch on my pump so that I could set it up and let it run to draw a vacuum. Worked but not that much elegance behind it. I particularly like the idea of making vacuum reservoirs out of PVC pipe. Cheap and not dangerous. I was toying with the idea of using an old propane tank from my barbecue but it's a pain to find the right fittings.

When I ordered the switch I did not read enough of the sight to understand that there was a link to joewoodworker.com that explained a more thought out system for working with a bag and reservoir. You can't learn any more from me then is on that sight my friend. Great resource. Thanks again!

Mark

 

[johnnyfamous]

yes it is a great site. I too like the pvc pipe, very cheap solution. At the end of the day though you still need to buy 2-300 worth of gear if you follow there recomendation, I think your system sounds a little cheaper and simpler, I like cheap! i dont use it enough to spend much money on the build.

So far the urethane glue is working well! I just set one of the top edges, we will see how she comes out

 

[mwmkravchenko]

Cheap is good as long as it works well. My timer switch did and does work. But it is not the best solution. But coupled with some vacuum reserve and that crazy little unloading switch I think it could be a very much better system fir less than a $100.

As for you if you want you can do the same type of setup with the compressor. I was thinking about this last night and it should work. If you make up the reservoirs and the un-loader system which by the way I think you can get the same solenoid valve from Princess Auto. I'll check on that one. You should be able to get a relay and wire it up to the compressor as if it was plugged into it. Just one big switch to turn it on and off at the will of the vacuum switch. You would need an oulet wired to the contactor side of the replay that the Vacuum switch could actuate. Normally a compressor starting current is 3 times the running current. That little vacuum switch does not have heavy enough contacts so they sell that relay to switch the greater load. You might even be able to pick up the relay locally. Save on the shipping.

Mark

 

[johnnyfamous]

Cut the top down to size, started veneering the ends. I use my trimmer to cut off the excess, i think some people do this by hand with a saw,, not sure why this way is quick and makes for a nice clean job.

 

[Bengoshi2000]

I'm LOVE-ing the inlay...

 

[johnnyfamous]

Made slow progress this morning. Its going to take a long time to veneer each piece. I am debating now if I should finish/clear all the pieces before I attach them to the box, would make finishing a little easier.

Spend most of my time waiting for the glue to set:foottap:

 

[mwmkravchenko]

Hi John

Looks like a real Pro job!

Can't wait for the finished pictures. I'm happy you have the polyurethane going so well for you. I'm still kicking myself for not telling you about that stuff first. Oh well. The top still looks good. And everything else you are doing is looking wunderbar.

Mark

 

[johnnyfamous]

Thanks Again Mark!

Have still bean gluing the veneer,,, slow... I was having issues with the glue seaping through the grain under clamp pressure and sticking to the pressing surface, Started using waxed paper between the veneer and pressing surface, problemo no more:heehee:

have been sanding the pieces and top smooth as i wait for glue to set, laid down a light seal coat on the top and one of the corners. starting to hear it play already:bigsmile:

 

[Mike P.]

That is simply gorgeous! Looking forward to seeing the finished product!

 

[johnnyfamous]

Thanks Mike!

A quick question to confirm, The PR came with 20 x 45 gram disks. for my tuning i will want to use only ten in each PR? Will there be any other difference from the original design given that i am using the 300 watt bash as apposed to the 500w?