vnail pushing my mitre apart

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bugman

Grumbler in Training
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Dec 2, 2009
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Adell, WI
I'm guessing this question may expose how new I am to this.

I purchased a used VN42. I am using 2 different moldings. One is poplar shadow box profile 3/4 x 2 3/4" tall. The other is white Ash and is only 3/4 x 1 1/4" high.

I am using a 15mm vnail and have my pressure set at 70psi. My tank preassure is actually at 120 but for some reason I can't set the machine beyond the 70? I am using both the horizontal and vertical clamps.

The miter cuts are good and my fences are set to 90 degrees.

Prior to driving the vnail everything looks good, but when the vnail goes in it pushes the miter apart. It is actually the worst with the ash if that gives a clue. The poplar only moves about 1/64 but enough to leave the slightest gap.

The vnails are going in straight.

I am going crazy trying to fix this and have wasted a lot of molding. Does anyone have any suggestions.:help:
 
Just off the top of my head..... I would hazard a guess and say that you may be using a soft hold down.

I would also look at when your hold down if firm, and when the nailer actuates. They aren't supposed to be simultaneous.

If they are going in straight on the ash, then you are using hard wood nails.... but I question the use of a 16 penny nail when a 16 gauge finish is needed.... try stacking a couple of 8s.
 
When you say a soft hold down are you referring to the pads on the vertical clamp?

I am pressing the actuator half way down to clamp first and then the rest of the way to drive the vnail.

I don't currently have anything but the 15s but I can order others.

Thanks for your help!!!!
 
In some machines, the only way you can keep tall profiles from tumbling over is to build a jig to hold it. This is particularly true when the rabbet in the back of the moulding causes it to be less than 1/2" wide or if the bottom of the moulding has rounded rather than square edges.
 
Thin-profile, heavily grained hardwood can the most challenging type of moulding to join, in my limited experience.

Can you better describe the problem? "Pushes the miter apart" could mean that the joined corner is open at the top, bottom, outside, inside, or all over. Where, exactly, is it coming apart?

If the moulding is moving (such as twisting, turning, or compressing) during the joining process, then you have a clamping problem. But I'm guessing that's not your problem.

The main cause of open-on-the-outside miters is that every wedge inserted splits the wood, just as using a wedge helps to split firewood -- except you're leaving the wedges in the miters. That is, each fastener has the effect of making the inside of the miter tighter, and the outside looser. Open-on-the-outside miters are symptomatic of using too many fasteners per corner, but my guess is you're using only one per corner in the wood you described.

Are you using the "Pulling Power" fasteners from Alfamacchine/Amp/Putnam/MiterMite? If so, that may be part of your problem. That feature consists of a bend in the geometry of the steel 'V', which is designed to pull the pieces of wood together, and it works for that purpose. However, the fastener's bend makes its profile thicker, so it tends to separate the wood a little more than a flat fastener would. I guess you can still get flat fasteners without the "Pulling Power" feature, which may work better in your particular case. They also stack better, without the top fastener splitting and blowing out through the finish.

The only sure cure: Assemble your miters in vices and dry the glue overnight. Then you can nerly always insert fasteners without opening the outside of the miters.
 
I prefer the "non-pulling-power" fasteners, and get them from V-Nail.com. The name brand fasteners used to jam in my venerable VN2+1, but these never do.
:cool: Rick
 
Your pressure is too low and you need to drop the hold down clamp to within 1/4" above the moulding before beginning the job. On the VN42 you need to pull the pressure adjustment knob out and it will click then you can turn it to adjust the pressure. If you are doing that and it is not increasing you have a second regulator for the line pressure on your compressor like I do. I set my tank pressure at 150 and my line pressure at 100. The pressure regulator on the VN42 stays at 80 unless joining Basswood or delicate finishes and that is the only time I drop to 70. For Ash moulding you need 90 and if it is extremely hard you need to go to 100. Be sure you vertical clamp is within 1/4" of the top of the moulding to begin with. Do not try to stack v-nails in Ash because it will almost always open the miter.
 
I have the VN42L which is basically the same machine as yours and I also have had that problem. It seems that the majority of the time it was because I tighten the angle of the movable fence to tight to the moulding so when the front clamp pushes the moulding to the fence it forces the fence to open. I now put the joint together dry before nailing and adjust the fence so it just touches the moulding. Once I adjust it properly then I will glue and nail it. There are a couple of profiles that are a PIA to work with so what I do there is adjust the fence as above but I remove the front clamp and hold the joint tight by hand. It works just fine that way. Also, there has been a few times that I have had to chop, glue, & clamp, but that has been seldom.
 
Ahh... you are all starting to make me feel better. Maybe it's not just being less experienced.

I am using Mitre-Mite 'power twist' fasteners. I will check with v-nail.com.

The ash is definitely a heavy grained wood but the poplar is really very fine grained.

I will try and better explain my problem.

Again I have verified the mitered cut, the fence angles and that the miter line of the mitered corner is positioned directly over the center of the vnail. The plastic pad attached to the vertical clamp is amber colored (in case if they are color coded for hardness) and I am using 70 psi. I have even taken the pad off using the metal surface of the clamp to avoid any potential give/compression of the pad which yielded the same problem.

Reading one of the last replies I will try and increase my pressure. Maybe I need to hook the air line directly to the compressor as it currently goes through a manifold and gets reduced to a smaller diameter line.

The top and bottom edges/surfaces of the profile are flat except for slight radiused edges and aren't causing any tilting.

I butt the two mitered pieces into position and they look great. The miters are tight. I can view the entire length of the mitered corner and everything looks great. I step on the foot pedal to apply the horizontal clamp, apply the vertical clamp and apply the fastener and the miter opens up slightly. Looking down at the corner with end 'v' shaped edge of the fastener showing, the joint is slightly separated and seems to pivot right where the fasteners 90 degree corner presses into the miter line of the corner. I am only using one fastener per side and it is being applied about a 1/4" from the outside edge as the molding has slots for the glass and backer. The fastener is just slightly embedded below the surface of the molding.

I have even built custom fences after talking with the equipment manufacturer tech support person as he said it was possible that the moving parts of the supplied fences may be worn and causing the problem. But even my new, taller fences are giving me the same problem.

I haven't had any blow out problems using just the one fastener on each side.

The use of vices would be ok except that I am typically assembling about 25-50 frames at a time. I use to glue and side pin using an air nailer before purchasing the vnailer. I really need to have the production ability though.

With the taller molding I apply another fastener at the opposite end of the molding with the same results.

I really appreciate the help and responses all of you are providing.

Thanks
 
Get the pressure up to 90 and be sure to use the 90 Degree hold down with the teflon pad (orange) in place. The pressure setting also applies that much downward pressure on the moulding prior to insertion. I have never preglued a frame for my VN42 and between mine and other VN42's I've used I've made over 20,000 frames on that model.

I never use any of the pulling power/power twist fasteners for various reasons. Once the pressure is up you'll have no problems.
 
Not that it helps your situation, but a little digression in praise of Cassese 299M ... if you have a truly super hard (or otherwise challenging) moulding you can lock the clamp for a few minutes while the Corner Weld sets up, and then shoot the nails as normal ... so much easier and faster than clamping separately. Of course the clamping is so effective on the 299M that it is a rare situation indeed that makes this necessary :)

Apologies for the digression!
 
As Jeff said you need to lower your vertical clamp to just above the moulding otherwise you don't have enough downward force to hold the joint together as the pin shoots in, also increase your pressure to as much as possible. My line pressure is only 85 lbs and with that moulding it sometimes helps to stack 10mm pins. I also do something a lot of people here don't like but I use soft pins for every moulding as I don't have problems with the joins like I do with med/hard pins.
 
All said and done, have you tried using clamps to pull them back together? Seems a waste of materials re-doing an already cut and joined frame, and using 36" clamps to pull them back in would do the trick.
 
Rick Granick said:
I prefer the "non-pulling-power" fasteners, and get them from V-Nail.com. The name brand fasteners used to jam in my venerable VN2+1, but these never do.
:cool: Rick
Click to expand...


Should a framer be concerned that non-Pistorius V-nails will void the Pistorius warranty?
 
cjmst3k said:
Should a framer be concerned that non-Pistorius V-nails will void the Pistorius warranty?
Click to expand...

No the V-nails are made to specs so there is no issues with warranty. There was a conversation about after market ink voiding printer warranties because they clog the heads and lines. The head assembly in V-nailers is a part that occasionally wears out and is inexpensive to replace and only covered under warranty for manufacturering defects.
 
Well, I have increased the pressure to as much as 95 PSI and I have lowered my vertical clamp to almost touching the molding and although it has slightly reduced my problem, my joints are still separating.

They continue to separate and pivot/rock at the point/corner of V-nail.

So I'm going to go ahead and try vnails.com fasteners and try some different sizes.

I will keep you all updated once I have resolved this problem in case someone else ever has this problem.

Thanks again everybody!
 
Be sure to buy the Med/Hard fasteners and do not stack them. The soft fasteners actually frature at the top once inserted into hard wood. The Softwood nails are sharper at the honed edge and that is why they split.
 
Jeff Rodier said:
Be sure to buy the Med/Hard fasteners and do not stack them. The soft fasteners actually frature at the top once inserted into hard wood. The Softwood nails are sharper at the honed edge and that is why they split.
Click to expand...

As I said in my post many here don't like soft pins for the reason you state, however the few times I had to pull a corner apart when using soft nails I have never had a broken pin.
Overall I have much fewer problems with the soft pins. I also sometimes find it easier to stack 2 10mm pins rather than using 1 15mm (where height allows) as it takes less pressure to drive the pin.

But then again what works for one may not work for another.
 
Bugman, if the fastener is driving all the way into the wood, then air pressure probably is not the problem. If the moulding pieces do not move when you engage the clamps, then set-up is probably not the problem. If the moulding pieces do not move when you drive the fastener, then set-up is definately not the problem. Using a different brand or type of fastener might help, but maybe not.

My guess is that the outside of the corner is open, and the inside of the miter is tight. Right?

Can you post a couple of photos showing different views of the miter trouble?
 
I have attached 3 pictures. One showing the joined miter with the persistent gab that I need to get rid of. One showing my setup including my custom fences and the last showing a joint before fastening.

I am getting some movement to the inside corner when I apply the horizontal clamp (it pushes it open ever so slightly). I have adjusted these fences and the original manufactured fences to try and stop it but have been unsuccessful. In fact it was this movement that made me think that the original fences may be worn and why I built the new ones. No difference.

I have even pulled the horizontal clamp away, and manually held the miter together and only applied the vertical clamp but the v-nail still pushes it apart in the same way. !@#$%^&*

I have left vnails.com multiple messages but they may be closed due to the snow being in NY.

Are there other economical suppliers?
 

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Are you only shooting in one vnail as in the picture?

I am thinking along the same lines as Jeffs posts.

Also is the cut a bit ragged? The leg on the left looks like it might be the problem.


Bob
 
Any chance it could be the mitres themselves? It can be difficult to get a perfect mitre on such a tall moulding. The small chips on the face of the moulding made me think about this possibility.

Have a sander?

I've had mouldings that looked like they were aligning perfectly but had gaps when joining...and it turned out that it was the cut.
 
I am just using one fastener on each end of the moulding.

The images are a bit magnified as they are only 3/4 thick but maybe the bit of fuss on the leading edge is causing the problem. I will kiss them with the sander and see.

The leg on the left is cracked, but I was using a piece of scrap for this picture.

I also have some non-power twist v-nails coming as well. They are rated for both soft & hard wood. I have been using the med/hard power twist fasteners.

Should I expect the inside corner to move at all when applying the horizontal clamp?
 
Lose the custom made fence. The fence is made to rock and roll when the horizontal clamp engages. The higher fence is exagerating this rock and roll. Move the horizantal clamp back one hole so it is not putting as mch pressure on the moulding. ITW/AMP makes a set of magenetic bar extenders that are only 1/4" square so the fence would be lower and eliminate the rock and roll. They also move the moulding forward from the fence so you get a better view. Once the horizontal clamp is engaged you can slightly adjust the top alignment of the moulding before dropping the vertical clamp.

Your picture of the V-nail looks as if the driver is slipping off the V-nail befor it is fully inserted. That is a low pressure issue.
 
In the second picture it looks like the lower clamp in not aligned to the nail block. Is it screwed down tight? If it is loosen it slightly and let it self align.
Also sand the mitres they look a little rugged.
 
Jeff Rodier said:
Lose the custom made fence. ...............

Your picture of the V-nail looks as if the driver is slipping off the V-nail befor it is fully inserted. That is a low pressure issue.
Click to expand...

I didn't like the fence either.

Increase the pressure and shoot at least 2 if not 3 nails.

One will give it too much rocking.

(In case you didn't know, Jeff joins more frames in a day than busy shops do in a month, definately a great resource to have)

Good luck.

Bob
 
As we can't see the top profile is it slightly rounded or flat.
If it is rounded it might be the neopreen hold down is making it rock.
I usually have better luck with a round softer hold down to even out the pressure.
Loose the extentions.
 
The first picture actually looks like a pin through the top of your moulding and like you have a profile mismatch. I agree the cuts don't look very good which could be a problem.
On tall moulding I set my fences to + and the first line on both sides (the back set of knobs) which slightly tilts the moulding to close the bottom making a good join along the back and adjust the first knob as appropriate to close the gap on top (according to how accurate the cut is to 45 degrees)
I agree I would lose the set of rails and use the 1/4 blocks if you have them so you can see the back.
I would play with the horizontal clamp and if the closest setting doesn't open the join I would use it as the pressure is greatest here.
 
Problem resolved... thanks everyone!!!

I got rid of my custom fences and went back to the original ones.

Once I did this I let the miter separate (rock & roll as Jeff suggested) if it wanted to at the top while pinning the bottom.

I used 10mm vnails from vnails.com, the non-power twisting kind that are rated for both soft and hard wood.

and I increased my air pressure.

Making those changes did it. Wow lots of time spent on this one but I learned a lot about the machine and I got some GREAT HELP from some real professionals on The Grumble.

Thank You... I hope to meet you all face to face some day.

Terry Weber (aka: The Bugman)

Happy New Year!!!
 
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