How to straighten rear cover? - UK Vintage Radio Repair and Restoration Discussion Forum

g7mzh Laurence · 14th Jan 2012, 7:32 pm

I have a Roberts transistor table top set, model RM30, that has the old-style case back. The problem is that the material (which seems to be a sort of lightweight chipboard rather than the usual layered paper) has become warped.

Is there any way of straightening this? Bending it is impossible, it's quite solid and would probably snap. I'm wondering if steaming it would help, or whether getting it wet might cause more damage.

Thanks in advance.

rgds
LAurence

G8VAT Wolfman · 14th Jan 2012, 10:59 pm

Don't know this particular model but it if the pulp was compressed with resin, just warming it might soften it enough to press.

If it is quite thick then it's gonna need a really good steaming possibly under pressure before attempting any sort of pressing.

Just a single dampening shouldn't do any harm but watch for any inking/printing or labels that might suffer.

brenellic2000 · 15th Jan 2012, 11:24 am

If it is 'fibre board', ie: compressed 'oiled hardboard' or glued wooden fibres (chip/MDF), then any introduction of moisture will expand the wood fibres and it is unlikely they will ever contract again except under very high pressure.

The safest method is to warm it on a flat plate over a radiator and keep it compressed under a heavy weight over 2 or 3 days. You may have to try agian....

Barry

g7mzh Laurence · 19th Jan 2012, 9:36 pm

Thanks; a quick burst with a heat gun and a heavy transformer seemed to have some effect, but providing extended periods of heat safely isn't really practical. I didn't fancy putting it in the oven!

In the meantime, I'll replace it with a suitable-cut piece of hardboard. It's a solid state set, so heat won't be a problem.

rgds
Laurence

14th Jan 2012, 7:32 pm	#1
g7mzh Laurence Diode Join Date: Feb 2010 Location: Sussex Posts: 3	How to straighten rear cover? I have a Roberts transistor table top set, model RM30, that has the old-style case back. The problem is that the material (which seems to be a sort of lightweight chipboard rather than the usual layered paper) has become warped. Is there any way of straightening this? Bending it is impossible, it's quite solid and would probably snap. I'm wondering if steaming it would help, or whether getting it wet might cause more damage. Thanks in advance. rgds LAurence

14th Jan 2012, 10:59 pm	#2
G8VAT Wolfman Retired Dormant Member Join Date: Jan 2010 Location: Yorkshire, UK. Posts: 293	Re: How to straighten rear cover? Don't know this particular model but it if the pulp was compressed with resin, just warming it might soften it enough to press. If it is quite thick then it's gonna need a really good steaming possibly under pressure before attempting any sort of pressing. Just a single dampening shouldn't do any harm but watch for any inking/printing or labels that might suffer. Last edited by G8VAT Wolfman; 14th Jan 2012 at 11:24 pm.

15th Jan 2012, 11:24 am	#3
brenellic2000 Octode Join Date: Aug 2006 Location: Rye, East Sussex, UK. Posts: 1,647	Re: How to straighten rear cover? If it is 'fibre board', ie: compressed 'oiled hardboard' or glued wooden fibres (chip/MDF), then any introduction of moisture will expand the wood fibres and it is unlikely they will ever contract again except under very high pressure. The safest method is to warm it on a flat plate over a radiator and keep it compressed under a heavy weight over 2 or 3 days. You may have to try agian.... Barry

19th Jan 2012, 9:36 pm	#4
g7mzh Laurence Diode Join Date: Feb 2010 Location: Sussex Posts: 3	Re: How to straighten rear cover? Thanks; a quick burst with a heat gun and a heavy transformer seemed to have some effect, but providing extended periods of heat safely isn't really practical. I didn't fancy putting it in the oven! In the meantime, I'll replace it with a suitable-cut piece of hardboard. It's a solid state set, so heat won't be a problem. rgds Laurence