The Framers Forum

Hi there. I’m new to framing. I find that my curved mouldings are getting damaged from the pressure of the pinning. What is the best way to combat this please?

Which machine are you using, the bung could be too hard or you have the bung too close to start with, what I do on soft mouldings is use a pencil rubber on top of the moulding, I find it very useful on spoon / scoops shape mouldings

Hi. I’m using an Alfamachine 44. I used to use a pencil eraser on my last machine which manual and was doing the same thing. I changed it for this before I got going. I’ll try that again. Thought there must have been a more technical way. If it works, that’s all that matters. I’ll let you know. Thanks

Mouldings get damaged by excess force being applied in ways that are not distributed in ways that adequately distribute the load to avoid forces concentrating locally with sufficient intensity to create damage. The solution to this problem, may be achieved by sometimes correcting a single problem and at other times, it may require correcting more than one issue, where the cause maybe a combination of issues. Some underpinners are more kind to mouldings than others. With manual underpinners it is possible to apply the pressure more gently, instead of just slamming the wedges in as fast as possible, so that the level of force applied is not excessive. Pneumatic versions of Euro underpiiners were fitted with flow rate control valves which restricted the rate of flow in the main cylinder, so that the speed of actuation could be controlled without changing the level of air pressure needed.

Some other underpinners where fitted with their own air pressure gauges and the air pressure could be increased, when joining hardwood mouldings, or reduced when joining softwood mouldings as required. The use of hardwood, or softwood top clamp pressure pads, or bungs, allow more, or less give in the clamping action, but sometimes other methods need to be employed to spead the force and the degree of contact as a further measure to prevent damage to more difficult, or more easily damaged mouldings. It is not unknown for extra bits of moulding, bits of wood, or other materials to be introduced between the top clamp pad, bung to either better spread the area of clamping, or to allow the clamping force to be applied in such a way as to not damage the moulding.

Different mouldings can require different solutions, or combinations of solutions and on occasions a bit of experimenting may be necessary to find the best solution. Some mouldings are just a PITA and some framers simply remove samples of that moulding from the displays and avoid that moulding for future use. I've found that problems with damaging mouldings while underpinning them can be a reason why some mouldings are discontinued and sometimes cleared at a bargain price. This is not always a problem, if you know how to take extra care when cutting, or underpinning, but you do need to know what you are buying and how to get around these problems, if you like to buy these clearance mouldings. Discounted clearance mouldings are often popular with hand finishing framers and there's not many difficult mouldings that hand finishing framers can't find uses for and ways to use, without being troubled by such problems.

When I used my (now retired) Euro pinner it had a hard pad with a very thin facing of felt. I made a triangle of
wood covered with 1/8" cork and wrapped with clingfilm. A bit of extra effort involved in manually placing it,
but it worked a treat. You could also reposition it to bear of the inside of deep scoops.

** The clingfilm could be changed periodically when it got covered with hardened glue oozings.

Hi Peter,

That is so sensible and so simple, that it's brilliant! Great idea!

I have a pneumatic underpinner and I find that if it is turned up too high I can damage the face of the moulding.

I have it around 3 - 4 for most mouldings, up to around 5 - 6 for hardwoods.

Sometimes I get dried glue on my pad and that can damage the moulding so make sure to wipe off any glue that gets on the pad and change it if it gets bunged up.

pramsay13 wrote
"Sometimes I get dried glue on my pad and that can damage the moulding so make sure to wipe off any glue that gets on the pad and change it if it gets bunged up."

If you use prospero tip (as I do) wrap the bung in cligfilm (I use handywrap) then just replace when needed, much easier than trying to remove old dried glue from the bung, I also use it on back plates on my underpinner for the same reason

Thanks everyone. It’s still very hit and miss with the scoop mouldings. I tried to make a reverse block of the moulding, but it’s hard to stop it jumping around. I’ll try and stick to flat frames from now on, but that’s not the proper solution. I’ll keep dabbling with it until I get it right.

Mark at Underpinnerspares.co.uk sells a white rubber "Tri Clamping pad", have a look in the CS88 section of spares. It has a funny shaped top, which i just cut off and glued to the metal clamp base. Its very soft and distributes the pressure better for softer mouldings than the L shaped felt pad.