I think you mentioned that you used the same stretcher bars as I do (from upper canada stretchers). If that's the case, you should have absolutely no problem getting the canvases drum tight using the keys. I've even hand tightened some large canvases by hand and then used the keys to get the canvas drum tight.
The StretchRelief pliers are definitely expensive. However, considering the time it would take to build something similar (enhancing a standard set of vice grips) would cost me more (in time and close enough to the cost) to make them. In my opinion these really are much better than vice grips. The surface area of the plate, the grid of spike grips, etc make stretching canvas very efficient and consistent.
Yes, I use the same bars. I think it could certainly be technique - but I'm thinking it has more to do with the varnish I use which IF I apply more than 2 coats - makes the canvas very thick and more difficult to tension.
The point raised in this thread about rippling therefore concerns me. I'm working with a different substrate - and putting all else aside, its a concern that I believe would be magnified when using my varnished canvas.
On keys, I have (sadly) had the experience of tapping a key into the bar to tighten a wrapped canvas only to find the key perforate the canvas - literally go through the other side. This has been a very frustrating situation - and reading their UCart website - it seems some keys need to be adjusted BEFORE you bang them in (ie ensure they are fat enough wedge so that the point of the key cannot slip through).
SO - since I managed to do that on TWO canvases (screaming could be heard within a 10 km radius) - my workflow is like this:
1. Assemble bars
2. Measure diam both ways to ensure they match within 1/8 of inch
3. STAPLE corners to prevent the bars from shifting when I stretch and to keep them square
4. Add keys to each corner (tap in enough to keep them there)
5 Wrap canvas (by hand)
6. Cut off excess canvas on corners as per the video I posted the other day (Mike saw it)
6. Use hair blow dryer to heat up corners of canvas (about 10 seconds on high)
7. After making the sign of the cross and 10 hail Mary's wrap the *&@ corners.
What I should do is add glue to keys as you do to keep them there.
It works. I have to discipline myself to make each corner a mirror image - in other words, the overlap should be on the top of the canvas, not the sides. I'm left handed so its something I have to practice and concentrate to ensure each corner is wrapped correctly as it is hard to fix.
As far as the pliers - they are overpriced but that was not the point - the point was - I'm not reducing my image size to 18" (vs 20) to allow 3 " on each side which is plier requirement and/or I'm not ditching my 24" printer (which already is underused and has a negative ROI) in order to spend another $5000 to buy a NEW printer just so that I can use these pliers.
When I checked websites on machine wrapping - they stipulate they need even LESS salvage than I currently have (if my memory is correct) which means I can get a wider bar (1 1/2") with 2" borders. THIS is appealing to me and something I want to test (ie outsource and have someone wrap one for me)
Bottom line: Glad it works for you and again, any donations towards a new 44" printer are welcome and appreciated