The Framers Forum

Dear all, am using a mitre trimmer/guillotine from DIY Framing and have noticed something curious. Wondered if anyone could shed any light.

Basically, as the blade finishes it's pass through the wood to complete the cut, it seems to hook so that if I keep the moulding tightly in place and withdraw the blade (still holding the wood tightly in place) there's a tiny gap between the inside of the mitre and the blade. I'm holding the moulding as firmly and tightly as I can from the start of the cut to the finish, and I've tried it on several mouldings, and on both sides of the trimmer, and get the same result every time. Problem is that all my mitres are tight on the outside but have a hairline gap on the inside

Is there anything I can do about this?

many thanks,
David

Pic showing moulding fitting tightly against blade at end of cut:

Pic showing gap left once blade is withdrawn:

It might be that the blades need sharpening.

Do mitre trimmers use hollow ground blades? If they are straight ground, they probably won't stay sharp as long as hollow ground blades.

Someone who knows what they are talking about, (perhaps Stewart at Lion), may be able to advise you about the best way of sharpening these blades to get the best results.

Thanks Mark. I did wonder about that, but the machine is only a couple of months old and hasn't done much chopping in that time, so they should be sharp. They were certainly razor sharp when I savagely cut myself on them when new!

Anyone else have any suggestions?

thanks v much
david

If it aint blunt blades then sounds like the fences are moving slightly.
Are the hex bolts tight in the base which clamp the 45 degree stops in place?
Are you just relying on the stops and springs to maintain the angle of the fences? They need clamping firmly as well with the thumbscrews on the ends of the fences.

I had similar problems.
We used a metal 45degree angle pressed tightly against the blade then the arm was brought into place.
We held it firmyl to ensure that we could not push the smallest feeler guage available on the market between either the blade and 45degree and the arm. We then tightened the butterfly screws with a pair of pliers. End of problem. Hope this works for you as well.
Regards
Heather

I have a similar machine, (branded Alexander), and have found that it is tricky to keep it correctly aligned. I often find that the fence has moved back a few mm from the casing under pressure, especially with wider mouldings. I've tried wedging the fences but have not yet come up with a foolproof method. Be wary of using pliers etc to tighten the thumbnuts - a friend with a similar machine did that and cracked the casting! If anyone has got this sorted I'd be very happy to know about it.

Thanks for the replies.

Interestingly I'm increasingly hearing from people that I'm worrying too much about the hairlines gaps in the mitres I'm trying to correct. Apparently this is par for the course and the solution is just to fill the gaps with wax or whatever. Having received this advice I actually took delivery of a few framed pictures I had ordered yesterday and there had indeed been some filling going on.

What do people think about this? I like to take pride in my work and so I'm not really comfortable with the imperfect job + patch up idea, particularly as I'm hoping I can differentiate myself from larger framing concerns locally on the quality of finish, but then a framer whose opinion I respect did point out to me the other day that we're dealing with wood and so perfection to the Nth degree might not be attainable. But you know, when I did my training with Mike Royall using the same equipment I've got now, I managed to produce a much better frame than I'm currently managing without any problem, and without filling.

Your thoughts?

thanks
David

Not all mouldings are equal David. Some cut and go together like dream and some are a PITA. Plus the fact that mouldings are mostly wood and wood is not perfectly consistent. So with the best will in the world you are going to have to compromise somewhere along the line. If you sorted your moulding stock and selected all the absolutely perfect stuff, you would probably have to reject about 80% of it. Maybe 10% will be just too ropey to use. Somewhere in what's left you have to decide a level of acceptabilty.

The worst will be stock that has a twist. You may be able to persuade it to a good alignment on small stuff. if the frame has a slight twist, the glass may pull it flat, but the frame will always be under a strain. (as will the glass) On large mouldings they have to be dead straight. If you have your blades set right there shouldn't be hairline (or credit card) gaps, but there will always be a tendency for one corner to not line up right. It happens on one corner (The last to be joined) because any twists on any of the rails will accumulate onto the last corner. that's why I always pin all the outer wedge positions first and then do the inner ones. That way any slight misalignments will normalise themselves and the misalignment will be spread among four corners and usually become imperceptible. (To the customer at least...... )

Thanks Prospero.

Does anyone else have any views on this?

thanks
David

I remember someone over the pond on the Picture Framers Grumble mentioning "a good mitre i.e. a join you couldn't fit a credit card into". I guess what constitutes a good join varies. Personally, as an inexperienced framer, I worry about gaps the size of a hair, although I *know* nobody else will probably notice.

Steve