[cctalk] Re: PDP 11/34 or 11/04 front panel question
On 2023/12/19 4:26 a.m., Tom Hunter via cctalk wrote: I just realised that I never followed up on this. After some research and a few phone calls to manufacturer support lines I settled on SikaBond SprayFix as the glue. ... The front panel has now been re-assembled and is fully functional and beautiful. :-) Might you have Before and After photos? Sounds like this is a useful product to have in the shop! Thanks, John :-#)# On Tue, Nov 7, 2023 at 9:33 AM Tom Hunter wrote: The PDP 11/34 and 11/04 front panels (both operator and programmer) use a somewhat stiff plastic sheet of 1.0 mm thickness with DEC logo, model designation, labels for the keys printed on it, cut-outs for the keypad and knob and red transparent sections for LEDs and 6 digit 7-segment display. I don't know what the industry calls this type of plastic sheet? Is it a "decal"??? This plastic sheet is (was) fixed to an anodized aluminium plate (1.6 mm thickness) using some type of glue which has deteriorated so that the plastic sheet has separated from the aluminium plate. The glue looks like it has been sprayed on and has a light yellowish-brown appearance. The glue readily dissolves in ethyl-alcohol and acetone, but is unaffected by water, petrol (gasoline) and dry cleaning fluid (white spirits). I would like to glue the plastic sheet back onto the aluminium plate, but worry about damaging the plastic sheet and/or paint by the solvents in typical glues. Also some glues don't allow any adjustment once you combine the two halves of whatever you glue together. What type of plastic is this plastic sheet likely made of (polycarbonate?) and what paint was used? I am asking to determine what solvent based glues may attack either the plastic sheet or the painted surfaces. The dark grey and transparent red paints are applied to the back side of the plastic sheet, so they are vulnerable to solvent attack when glueing. I tried ethyl-alcohol in one corner which is obscured by the cast metal surround and some of the dark gray colour came off with the alcohol and gentle rubbing. Has anyone successfully glued back the plastic sheet to the aluminium plate? If yes, what type of glue did you use and how exactly did you do the operation? Any suggestions, advice or tips? Thanks and best regards Tom Hunter -- John's Jukes Ltd. 7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 Call (604)872-5757 (Pinballs, Jukes, Video Games) flippers.com "Old pinballers never die, they just flip out"
[cctalk] Re: PDP 11/34 or 11/04 front panel question
I just realised that I never followed up on this. After some research and a few phone calls to manufacturer support lines I settled on SikaBond SprayFix as the glue. The glue is advertised as "contains no chlorinated solvents", is "suitable for indoor use", is based on a "synthetic polymer", is "repositionable for 1-2 minutes" and has a "low odour". Sounded just right for this application. I first tried the glue on the bottom left of the plastic sheet which is normally obscured by the cast metal front. Next morning there was no indication of any paint damage in the sprayed area. I cleaned the aluminium plate with aceton and the plastic sheet with ethyl-alcohol. I built a jig out of a timber board with two thin metal rods inserted as alignment pins matching the alignment holes in the aluminium plate and plastic sheet. I then masked the red transparent areas of the plastic sheet with low-tack masking tape to prevent glue from getting onto them. This keeps them nice and clean for good visibility of the LEDs and 6 digit 7-segment display. With the aluminium plate mounted to the jig I applied a thin layer of the glue and then the same onto the plastic sheet which was laid out on a sheet of paper. I then moved the plastic sheet onto a fresh sheet of paper to avoid contamination of the front side with glue while I removed the protective masking tape. Finally I assembled the plastic sheet onto the aluminium plate with the aid of the alignment pins and immediately pressed the two halves firmly together. After a few minutes I removed the now securely glued assembly from the jig, flipped it over onto another fresh sheet of paper on the edge of a flat table with the plastic down onto the paper. I placed some weights onto the top (i.e. the aluminium sheet) to let it dry and bond for a few more hours. The front panel has now been re-assembled and is fully functional and beautiful. :-) On Tue, Nov 7, 2023 at 9:33 AM Tom Hunter wrote: > The PDP 11/34 and 11/04 front panels (both operator and programmer) use a > somewhat stiff plastic sheet of 1.0 mm thickness with DEC logo, model > designation, labels for the keys printed on it, cut-outs for the keypad and > knob and red transparent sections for LEDs and 6 digit 7-segment display. > > I don't know what the industry calls this type of plastic sheet? Is it a > "decal"??? > > This plastic sheet is (was) fixed to an anodized aluminium plate (1.6 mm > thickness) using some type of glue which has deteriorated so that the > plastic sheet has separated from the aluminium plate. > > The glue looks like it has been sprayed on and has a light yellowish-brown > appearance. The glue readily dissolves in ethyl-alcohol and acetone, but is > unaffected by water, petrol (gasoline) and dry cleaning fluid (white > spirits). > > I would like to glue the plastic sheet back onto the aluminium plate, but > worry about damaging the plastic sheet and/or paint by the solvents in > typical glues. > Also some glues don't allow any adjustment once you combine the two halves > of whatever you glue together. > > What type of plastic is this plastic sheet likely made of (polycarbonate?) > and what paint was used? I am asking to determine what solvent based glues > may attack either the plastic sheet or the painted surfaces. > > The dark grey and transparent red paints are applied to the back side of > the plastic sheet, so they are vulnerable to solvent attack when glueing. I > tried ethyl-alcohol in one corner which is obscured by the cast metal > surround and some of the dark gray colour came off with the alcohol and > gentle rubbing. > > Has anyone successfully glued back the plastic sheet to the aluminium > plate? If yes, what type of glue did you use and how exactly did you do the > operation? > > Any suggestions, advice or tips? > > Thanks and best regards > Tom Hunter > >
[cctalk] Re: PDP 11/34 or 11/04 front panel question
On 11/6/23 19:33, Tom Hunter via cctalk wrote: Has anyone successfully glued back the plastic sheet to the aluminium plate? If yes, what type of glue did you use and how exactly did you do the operation? Any suggestions, advice or tips? Thanks and best regards Tom Hunter 3M markets several different types of double-sided adhesive sheets that can be positioned by applying the sheet to one part and then wetting the other part, usually with Windex. Once you've got the position correct you squeegee the liquid and any bubbles out to the edges. I couldn't say whether the adhesives would damage your plastic, but given that there's no curing involved I doubt there'd be any at all. If you're willing to endure some hold time 3M might even help you with that. Doc
[cctalk] Re: PDP 11/34 or 11/04 front panel question
Thanks for the suggestion Tom. I have thought about it, but it would have to be a very thin type of tape. Also very precise positioning of the plastic sheet onto the aluminium plate is required as once the tape sticks to the other half it won't allow for repositioning. Some form of solvent free glue which does not attack the paint would be better as you can reposition at least for a few seconds. On Tue, Nov 7, 2023 at 3:33 PM Tom Ivar Helbekkmo via cctalk < cctalk@classiccmp.org> wrote: > Tom Hunter via cctalk writes: > > > Any suggestions, advice or tips? > > Have you considered simply using double sided tape? > > -tih > -- > Most people who graduate with CS degrees don't understand the significance > of Lisp. Lisp is the most important idea in computer science. --Alan Kay >
[cctalk] Re: PDP 11/34 or 11/04 front panel question
Tom Hunter via cctalk writes: > Any suggestions, advice or tips? Have you considered simply using double sided tape? -tih -- Most people who graduate with CS degrees don't understand the significance of Lisp. Lisp is the most important idea in computer science. --Alan Kay
