Open Mitres

[Elfyn Hughes]

I am getting mitres that are open on the inside (sight edge) of my frames. I have set up my Morso according to the manual and also using Pete Bingham's preferred method, so far without improvement. Do any of the gurus on this forum have any ideas.

[absolute framing]

Hi There,

It sounds to me as if the problem is with your underpinner. (if you have one). If you do have a look at your manual, with the Cassise Range, which i have, there is an angle adjustment screw on or near the right back-fence. If the corner is open towards the outside - turn anti-clockwise, of if open towards inside - turn clockwise.

Hope this is of some help,

Stephen

[Roboframer]

I always re-calibrate angles on both Morso & underpinner with a piece of flat pine batten, about three and a half wide by three quarters deep. Any errors will be obvious. If your morso is out your underpinner can't put it right.

Another way to check your underpinner fences is with a large right angled set square, adjust the fences to butt up to it if they don't already. Once that is set and you still have problems it must be the morso blade angles.

[markw]

If you have a gap on the inside sight edge then its almost always a cutting problem. Do you get the gap on the first join - or is it only present on the last?
If the answer is yes to the second question then the answer is almost certainly your Morso - or your cutting technique.

Try this simple test - make sure that you take the first cut well into the start of the moulding so that you cut a V shape - if you just cut off the first angle as a 45 degree bite then you risk getting a bad cut as the blades cutting force is thrown out of balance. Just to make sure you are getting a good stable cut clamp the moulding into place on your morso on both sides of the bed. lastly take lots of small bites and make sure the last one is fairly fine.

If this works and gives you the result your after then I would look at the sharpness of the blades and their alignment on the machine as the pressure exerted by the blades must be evenly spread to both sides of the cut - get this pressure out of balance and you wont get a perfect cut - clamping it will help keep the moulding in a more stable position than just holding it and may just allow you to get a perfect cut, but will hopefully prove that you have a problem with the blades.

When did you have your blades sharpened?

[John]

Mark has said it all. Read carefully and follow his suggestions and you should eliminate the problem.

Occasionally it is necessary to clamp certain large mouldings to prevent movement as they are being cut.

[Elfyn Hughes]

Thanks to all of you who replied.
Perhaps I should expand a bit on my original post. I use a Euromouldings underpinner which has a fixed fence, but I suspect the problem is with the Morso settings rather than the underpinner.
The mitres are being cut at slightly less than 45deg so that when I come to the last joint, the ends of the frame overlap, joining it then causes the mitres to open slightly at the sight edge.
I replaced the blades about four weeks ago with a set sharpened by Lion, so I think the blades are OK. My next step is to take the blades off and refit them, or try another set, but I am rapidly running out of ideas, and what little hair I have left is being pulled out!

[markw]

If your getting a problem at the last join then its either - inaccurate cut angle - check for squareness of set up. the moudling is being cut at fractionally different lengths. check that the stop is not slipping - this can happen if you dont back offthe blade and guides between cuts - the rebate stops push on the moulding and force the length stop to move fractionally - it doesnt take much to cock up a perfect mitre.

[Not your average framer]

I started getting a similar problem, but only on hardwood moulding. It took ages to figure it out and was really driving me nuts. Eventually after a long time, I finally worked out what was happening. Mine's a Morso model F, vintage 1995 and has the aluminium vernier measurement system, but over time the short rule on the measurement system had become worn un-evenly so that with the extra sideways pressure when cutting hardwood, the 45 degree end of this rule would move away from the main rule allowing the cut length to increase during the cut and changing the angle.

Later Morsos have solved this problem by allowing the clamp to side up and down the short rule so that for most frame sizes the rule can be clamped near to the 45 degree end. The newer machines have stops at either end so the clamp does not drop of the ends. On my machine the clamp is fixed to the small rule with a screw and does not slide, so I bought a second clamp to fit on the 45 degree end and the problem was solved.

Might been worth checking for this problem if your machine is similar.
Cheers,
Mark

[cmaclean]

I'm glad someone else is having troubles with open frames on inside edge.
I get moulding supplied already chopped to suit my artwork, and it suits because I have a small shop with not much room for stock.

I've had difficulty in joining the frames with my underpinner, I suspected the chops but it was only when I laid the frame out on a flat surface and strapped it with a strap clamp that the problem became totally apparent. The high point on every corner of the frame was the outside edge leaving 0.5mm gap on the inside on every join.
With some of the info on this forum I'll couch a reply to the supplier and ask them to check their gadgets.
I've solved the problem for the moment by trimming the moulding with my morso BA and then gluing and joining them.
Cheers and thanks

Campbell

[markw]

Campbell - in my experience the moulding suppliers who offer chop dont take as much care as they should - they give the job to the nearest employee and tell him to get on with it - they then just treat it as a simple job of getting the length right - no care taken in setting stops - checking machine for sharpness etc - result - crap joints. I use chop for 99% of my jobs - I can tell you when the chap who normally does it has gone on holiday by the subtle difference in the cut. Some suppliers also make up readymades - they tend to have far more experience of the problems presented by poor cutting - they notice the blade needs sharpening. Chop can work - just find a good supplier.

[Dermot]

One way of eliminating bad mitres with chop is to use a mitre sander such as the Logan http://www.logangraphic.com/products/fr ... nder.shtml

You order your chop fractionally over size and then finish them in your own shop ……..from following the US Grumble I have gathered that the Logan is OK for light usage but that ITW AMP sander is what the heavy usage shop needs……….the use of a mitre sander is very common in the US where chop services are very developed….

Lion sell the Logan

I don’t know who sell the ITW AMP in this part of the world http://www.itwamp.com/customintronew.htm

Rgs

Dermot

[markw]

When I pay for a service i expect to get what I pay for - chop costs considerably more than length - you should expect to be able to assemble a chopped frame and have perfect results every time. Sanding a frame with the sort of kit illustrated in Dermots reply would introduce a small difference in length that could eventually lead to open mitres. I suspect that many companies who chop use up all the odd bits to save money - warped - mismatched etc - your paying for a premium service - send it back.
In the UK I would recommend Ashworth & Thompson and Nielsen - they both produce a very high quality product that can be assembled to give perfect results.

[michelle]

Hello,
I am tearing my hair out struggling to find out what I am doing wrong, I have ( for the first time) just replaced my morso blades and after what feels like hours of adjustment am still getting an open mitre on the back edge at the bottom ( it is fractional but annoying and not acceptable) So I head into the framers forum for an answer and find this:

I always re-calibrate angles on both Morso & underpinner with a piece of flat pine batten, about three and a half wide by three quarters deep. Any errors will be obvious. If your morso is out your underpinner can't put it right.

Another way to check your underpinner fences is with a large right angled set square, adjust the fences to butt up to it if they don't already. Once that is set and you still have problems it must be the morso blade angles.

which is most helpful, however if you have time could you please explain what you then do about the " obvious errors". I am assuming it is my incompetence at calibrating the morso as this is the only thing I have changed. I can't fathom out which bit to adjust blades/fences for my particular problem and can't find reference to it on the forum.
Hope you can help

many thanks
Michelle

[markw]

If your Morso was ok before blade replacement it should be ok now and it must be something wrong with the new blade or the way you have fitted it.
First thing I would check is that you havent trapped any bits of muck under the blade. Blade should be tightened up evenly and should meet evenly at the front edge.

Robos method of using a batten is good advice as it eliminates the chance of the moulding rocking when cutting - you wouldnt be the first person to spend hours adjusting a Morso only to find the moulding being cut wasnt as flat as it could be.

* blades that come back from being sharpened sometimes have a little burr on the cutting edge - a few passes of a smooth carborundum stone will remove this and will give you a better cut.

[michelle]

Thanks Markw
I have re-set the blades twice with no obviouse signs of dirt etc. The blades are brand new and cutting really smoothly and cleanly. I did move the fences in order to get easy access to the blades and have spent time and effort getting them accurately back, I read earlier on this post that moving the left fence slightly in would solve an opening on the inside mitre. Is there an equivalent knack of the trade for the rear of the mitre or do you still think it could be my blades?
sorry to keep troubling you and thanks for your time
Michelle
ps I have tried a very square solid moulding for checking and still have the problem

[Roboframer]

Try this link

http://www.thegrumble.com/showthread.ph ... ight=morso

Or contact Morso

http://www.morso-guillotines.dk/

[foxyframer]

On the Morso pull back the left hand fence a fraction towards you, so that when the frame is assembled the last mitre pulls the other three into a perfect tight sight-edged frame. Always take a look down the length of a moulding to see if there is a slight bow (inwards) and alter left fence back accordingly. Adjust to much and the gap will appear on the outside of the mitre. With practice you will get a perfect frame every time.
A slight reverse bow; then leave the fences in a straight line.
Also always make sure that the rebate is properly supported so there is no movement when the blades slice.
Framing was never an exact science or art.