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Cabinet and Chassis Restoration and Refinishing For help with cabinet or chassis restoration (non-electrical), please leave a message here. |
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19th Jan 2018, 10:41 am | #21 |
Octode
Join Date: Jun 2004
Location: Hampton Vale, Peterborough, UK.
Posts: 1,698
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Re: Milliput epoxy resin putty
Just use fingers, water-wetted. I find Milliput tends to stick to thin rubber and plastic gloves. The stuff is temperature dependent, as already pointed out, so work in a warm environment.
Reinforcement is important when the area of attachment is small. Extracting a screw to leave the threads behind is, I think, going to be difficult - silicone grease notwithstanding, so an experiment is essential to my way of thinking. Piano wire is excellent for reinforcing pins (Ebay was my source) I rebuilt a plastics radio case using Milliput: https://www.youtube.com/watch?v=3sCopbnPED0 The video would show you just how versatile Milliput is. Tony |
19th Jan 2018, 11:17 am | #22 | |
Hexode
Join Date: Aug 2014
Location: Dartford, Kent, UK.
Posts: 435
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Re: Milliput epoxy resin putty
Quote:
My idea is that this Putty will form more of a shoulder for the bezel, see previous pictures, to rest on as the existing thread is still intact and that the 'trick' will be to remove the screw and leave a useable thread in the Putty once it has set. So I am going to wipe a similar screw with silicone grease and set it in the Putty, allow it to set and then see how easy it is to remove or not. |
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19th Jan 2018, 7:25 pm | #23 | |
Dekatron
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,766
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Re: Milliput epoxy resin putty
Quote:
If the repair isn't successful, I think the only possibility of a repair that will have lasting structural strength to enable a screw to be inserted to hold the dial retaining clip would be by drilling down into the Bakelite boss and tapping it 4BA. To drill into the boss you'd need to use an extra long (EG, 200mm) 3mm drill bit (4BA tapping size) to drill at least 25mm down into the boss, then to tap the hole 4BA as per the original, and to use a 22mm long 4BA cheese head screw to fix the clip. The drill bit must be long enough for the chuck to be clear of the cabinet to make sure that the drill is perpendicular. I guess that the cause of the damage was that the screw was just a fraction too long - maybe a washer missed off - so the screw 'bottomed' in the hole, stressed the Bakelite boss and caused the fracture, so do guard against 'bottoming' the screw. It would be wise to first drill a 4mm hole into the Milliput so that when tapping, the Milliput isn't put under strain. I don't think such a small area of Milliput would stand being threaded with a tap. Having drilled into the Bakelite, you'd probably first need to use a 4BA taper tap to start the thread, followed by a second, and a plug tap. You'd have to use a small adjustable spanner to rotate the tap, while pressing down on the top of the tap at least until the thread starts to bite. I've attached a sketch to show what I mean. Long, and extra long drill bits are available, for example, here: http://www.ebay.co.uk/itm/HSS-Super-...26.m2548.l4275 If you don't have 4BA taps, you can get a set of three from RDG Tools here: https://www.ebay.co.uk/itm/RDGTOOLS-...-/370595504590 Hope these suggestions might be of help. Every good wish for a successful repair John.
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David. BVWS Member. G-QRP Club member 1339. |
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19th Jan 2018, 8:08 pm | #24 |
Hexode
Join Date: Aug 2014
Location: Dartford, Kent, UK.
Posts: 435
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Re: Milliput epoxy resin putty
Hello David, thank you for a comprehensive view of the problem and the draw backs.
I have literally just rolled out the test piece of white Milliput. It is difficult to know if it is mixed properly as both parts are white. On the face of it the problem looks very simple but I think that I will have to take my time on this one to get it right, especially as I am not to good with mechanical task. The radio may have had a bash in its life time as there is a chip in the case speaker ring, dent in the speaker grill and this may have helped this situation on its way. The back cover was held on with self tappers and the first IF transformer was replaced by cutting a hole in the chassis to make one from another Bush set fit! The case is the White Ivory plastic material.I cannot remember the name of it but it may handle better than Bakelite? Drilling with a long bit is OK but getting a relatively short tap to fit properly in such a small place, accurately, is doubtful at best. Another option that I am thinking about is completely filling the gap to the right of the pillar as well with Milliput to provide a larger anchor point. It would not look as nice but it may provide the stability needed. Once again thank you for your advice it really is appreciated. |
20th Jan 2018, 12:34 am | #25 |
Hexode
Join Date: Aug 2014
Location: Dartford, Kent, UK.
Posts: 435
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Re: Milliput epoxy resin putty
Well the results of the test went well. Two wall socket screws were encased in Milliput, one wiped in silicon the other not and left to dry for 6 hours.
Both of the screws came out fairly easily and the was only a slight difference in effort to remove them. Once an initial turn was made they came out and screwed back in very nicely. I am reasonably confident that it could work but the only issue that I see now is make the Milliput stick to the repair area and I am not too keen on drilling holes for pins and the like. It could be that there is enough of the old thread left to take the tension and the Milliput will just act as a spacer? |
20th Jan 2018, 9:50 am | #26 |
Octode
Join Date: Sep 2004
Location: St. Albans, Hertfordshire, UK.
Posts: 1,478
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Re: Milliput epoxy resin putty
This is going slightly OT from the thread title, but before the days of Milliput I had good results using ordinary slow-set Araldite. You can fashion a "mould" using Blu-Tac in the case to limit where the Araldite flows to, and screws can be moulded in using a release agent of your choice. If there is a little thread left in the plastic then the screw can be located easily. The Araldite sticks very well to the broken edge of the plastic.
Or, *bodge warning*, try it using Milliput and when it breaks away glue it back with normal epoxy!
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Regards, Richard, BVWS member |
20th Jan 2018, 10:51 am | #27 |
Hexode
Join Date: Aug 2014
Location: Dartford, Kent, UK.
Posts: 435
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Re: Milliput epoxy resin putty
Yes, I think the choice now is either getting something to stick sufficiently well to the 'plastic' case or tap the hole further and fit a spacer.
The Milliput looks 'likely' to fail at some stage and I have never got Araldite to do want I want it to! I do have a Dremel 3000 with a stand that I got this Christmas but I haven't used it yet. The long 3mm drill bit that David pointed out stands a chance of reaching it but getting the hole centred will be challenging with the shape and size of the case not to mention a relatively bendy drill bit. There is also a long shaft 4 BA tap on eBay that can be used if it is possible to drill a suitable hole. While the cream case is not perfect it would be a real shame to mess things up on the first and only attempt that can be made to fix it. |
20th Jan 2018, 11:02 am | #28 |
Octode
Join Date: Sep 2004
Location: St. Albans, Hertfordshire, UK.
Posts: 1,478
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Re: Milliput epoxy resin putty
If you try Milliput and/or Araldite and it breaks off then you've lost nothing and you can think about something more invasive!
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Regards, Richard, BVWS member |
20th Jan 2018, 11:28 am | #29 |
Dekatron
Join Date: Jun 2013
Location: East Sussex, UK.
Posts: 3,327
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Re: Milliput epoxy resin putty
You may find an ordinary 4BA tap will fit into a small size nut spinner. Even a loose fit will be good enough to tap into plastic. Done that several times myself.
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20th Jan 2018, 11:49 am | #30 |
Heptode
Join Date: Feb 2006
Location: Marlborough, Wiltshire, UK.
Posts: 917
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Re: Milliput epoxy resin putty
I have found that excellent as it is, milliput does not adhere very well to other materials. Best sucess was a combination where the millput part (formed but unset) was affixed using a thin layer of slow araldite. Milliput does take a long time to cure, several days really.
Ken |
20th Jan 2018, 1:37 pm | #31 |
Banned
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
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Re: Milliput epoxy resin putty
If it comes off, superglue it back!
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26th Jan 2018, 7:16 pm | #32 | |
Hexode
Join Date: Aug 2014
Location: Dartford, Kent, UK.
Posts: 435
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Re: Milliput epoxy resin putty
Quote:
I have not attempted to file/sand down the repair as it will not be visible and hopefully it will have a bit more strength although I may do this on future repairs made this way. you will notice some discolouration to the repair which was caused when I left the bezel retaining clamp in place while the Milliput was setting. |
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30th Jan 2018, 12:47 am | #33 | |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
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Re: Milliput epoxy resin putty
Quote:
Hey Tony, I just watched your video and it's nicely put together and very clear and informative ... great 'handrail' for people new to the biz of the time-consuming but worthwhile art of cabinet restoration...and it shows what amazing results can be achieved. What is the type of the Ferguson you feature? I definitely had one in my collection as a teenager of 17 years old - which is when I owned probably six or seven valve radios and as many transistor radios - far more than I have now! But that was one of the valve models, 100% certain! Back to topic, a wonderful display of some very skilled cabinet restoration indeed; kudos to you! Thank you
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Al |
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30th Jan 2018, 1:12 am | #34 |
Hexode
Join Date: Aug 2014
Location: Dartford, Kent, UK.
Posts: 435
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Re: Milliput epoxy resin putty
I agree - it puts my first attempt in the shadows!
Just a thought, could paint or some kind of colouring be added to the Milliput mix? It would not be an exact match but it would take the edge off of a small internal repair like the one that I made. |
30th Jan 2018, 1:24 am | #35 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
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Re: Milliput epoxy resin putty
Hey John, I'm by no means a cabinet repair expert such as Tony, but I do use quite a lot of fillers and 2-part epoxy resins of various types, to stick one heavy thing to another, or to tolerate mechanical stress!
It seems counter-intuitive for it to be a good idea for paint or colouring to be added at the mixing stage, as there is a strong chemical reaction going on. I don't know if some of the water-miscible dyes ( I sometime use Kedia dyes for wood staining - absolutely beautiful) would be ok. It's an interesting question and I'd love to hear others' thoughts on it, too.
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Al |
30th Jan 2018, 11:16 am | #36 |
Octode
Join Date: Jun 2004
Location: Hampton Vale, Peterborough, UK.
Posts: 1,698
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Re: Milliput epoxy resin putty
Al, John -
Thanks for the warm words! The set is a Ferguson 'Flight' - at least, that's what the emblem on the front said. This is a little odd, as the only Ferguson 'Flight' I can find any record of is a transistor receiver. The one in the video is definitely valve. It's a good few years back and all I have now are a few photos, most of which are in the video but I believe it was AM/FM, printed circuit, so it would have been manufactured late sixties or into the 70s, I guess. The cabinet was Bakelite, which accounts for its fragility. When I obtained it, the thing looked as though it had been smitten in anger many, many times. Strange things some people do. I've never tried to add colour in any form to Milliput. Nothing to lose by doing so, water-miscible or otherwise, though the white of the superfine Milliput is likely to take a bit of subduing, I suspect. The main problems are two-fold: 1, getting the colour close enough to the original and 2, achieving a surface of the same reflective index. The Ferguson in the video was resprayed, so neither of those difficulties arose. Tony |
30th Jan 2018, 12:08 pm | #37 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,349
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Re: Milliput epoxy resin putty
It is possible to add colour to Araldite. In the Submarine Cables lab at STC where I had a summer job, each bench had a small tool kit which included a pack of Araldite and a bottle of Titanium Dioxide powder. They used to mix in a small amount of the powder when using Aralide for encapsulation to improve its appearance.
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