New to framing - Corner gap, maybe underpinner

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Briantj

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Hi,
I am brand new to the framing world, and had a sure belief that there should not be many problems in a 90 degree joint. however, I have had some issues that I think stem from my underpinnings. The corners of the frame can be assembled perfectly on a table, but when I put a clip in, I see a small gap, the same length as the clip is, if I slide the clip in from the front of the frame, then the problem is moved to the front of the frame , and therefore I do not think it is due to the cut of the frame.
as I said, I am brand new to this world and all the help, tips and anything else I can get will be greatly appreciated.

my underpinner is an AMP U-400. I use the original "power twist" clips, I have "soft" and "medium" clips, and I have generally only done tests with soft, since my frames are soft, I have 6,5 bar into the machine, from the compressor system, and I have set the machine to anything between 2 and 6,5 bar during different tests, but I did not think there are any regularities in the joints. my current frame size is 15mm wide and 20-25mm high.

thanks in advance.
from a new frame maker.

The hammer - should it come this far up?
Hammer.jpg


The cut before joining
snit.jpg



Some test frames
test rammer.jpg



Backside of the frame
Bagside af hjørne.jpg
 
Does the vertical clamp align with the insertion point?
 
The only solution I have found for that problem is to glue and vice the miters, then drive the v-nails after the glue sets up for at least several minutes. Sometimes shifting the v-nail positions toward the inside of the miter joint helps, but not always. Also, inserting the outer v-nail first helps sometimes, but again, not always.

V-nails in miter joints work the same way that a wedge works in splitting firewood. The length of the miter is expanded by the thickness of each v-nail. So, using more v-nails amplifies the problem, and using fewer v-nails probably would help.
 
You're putting too many v-nails in that width frame. The v-nails displace the wood when they are driven in.
Those appear to be hardwood mouldings, so trying the hardwood v-nails might help.
Jim's suggestion of glueing, then underpinning would probably help a lot.

On a lighter note, Your machine is equipped with an MC Hammer...
(Hey, somebody supply a Gif here!!!)
 
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download.jpg
 
Sorry, best I could do on such short notice.
 
Much better!!
 
Back to a more serious note.

If you are going to be doing a lot of frames with that kind of profile consider getting a Hoffmann dovetailer. Far superior to v-nailing with stem profiles.

Nice touch in wrapping the grain around the corner.
 
Thanks for the reply everyone.

I had probably hoped to be able to make them completely tight, without the use of glue. but it must, of course, be considered whether this is the path needed.

it's pinewood, with oak veneer, so "soft" wedges should be the right ones, right?

i only put a single v-nail in now, where is the most optimal to put this? 1/2 inside or approx. 2/3, measured from outside of frame?

If I have to get closer to a tight joint, is it my underpinner or Morso cuts I should look at?

thanks again!
 
Glue is what holds the joint together.
The v-nails are designed 1. to act as an internal clamp to hold the joint together until the glue dries, and 2. to act as a fail-safe should the glue joint fail. Despite misuse and lots of misinformation, v-nails are not intended to be used without glue.

Placement of the v-nail should be closer to the inside of the frame than the outside, but exactly where is something you will have to experiment with. A lot is determined by the grain of the wood and the consistency of the density. V-nails can be deflected. Pine, depending on species, can be either a softwood or a hardwood.

It looks like the Morso is doing a fine job, so working with the underpinner to get optimal placement is the path I would take.
 
To be pedantic Wally, pine is always a softwood, it just isn't always a soft wood.
 
Tell my aged southern yellow pine floors that they aren't a hardwood.
 
Of course it is categorized as a softwood, but try putting a softwood v-nail in it.
Point being is that deciding which v-nail is appropriate is determined by the density of the wood, not its classification.
Southern white maple is called a hardwood, but it is slightly more dense than Basswood.
 
wpfay said:
Of course it is categorized as a softwood, but try putting a softwood v-nail in it.
Point being is that deciding which v-nail is appropriate is determined by the density of the wood, not its classification.
Southern white maple is called a hardwood, but it is slightly more dense than Basswood.
Click to expand...
That's why I use the fingernail test to determine which vnail to use.
 
You've come to the right place (forget that other place where some will tell you this is acceptable, or even really good!)

With an overall width of 15mm, you only have 9 or 10mm left for V nails so two positions is one too many. One position about where your inner one is, or slightly nearer the back. For the 20mm deep moulding I'd use one 15mm V nail or stack two 7s. For the 25mm one I'd stack two tens. Plenty of glue, always.

If it was a hard wood I wouldn't attempt stacking and would probably need to clamp it while the glue dries, then I'd toss the sample and replace it with what you have, a veneer on soft(er) wood. (That's what I actually did - all my PITA oaks got swapped for veneers - still had plenty of solid oaks that were not a PITA though)
 
Hi

I have not been too good at answering back in here, but the status today is that I have put a bigger presser foot on my morso, and at the same time put a piece of veneer on. at the same time, I have experimented with a soft wax for the corners, and I have started gluing my joints on frames, with more than 700 mm, on one of the sides.

Feel free to share your thoughts on this. thanks.

The pictures show my morso setup, as well as one of my worst corners.
 

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To repeat Wally's earlier point, glue is what holds the corner together. The mechanical fasteners secure the miters until the glue dries (unless you leave the corner in a vice), and then prevent catastrophic failure in case the glue bond is broken by force, such as impact. BOTH glue and mechanical fasteners are always needed.
 
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