How to unstick center disk of round slide rule?
in [Design]
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From: Joerg on 24 Feb 2010 20:12 Paul Hovnanian P.E. wrote: > Joerg wrote: >> Paul Hovnanian P.E. wrote: >>> Joerg wrote: >>> >>>> JosephKK wrote: >>>>> On Fri, 19 Feb 2010 18:51:53 -0800, Joerg <invalid(a)invalid.invalid> >>>>> wrote: >>>>> >>>>>> Paul Hovnanian P.E. wrote: >>>>>>> Joerg wrote: >>>>>>>> Gents, >>>>>>>> >>>>>>>> My round slide rule is developing a sticky center wheel. I can still >>>>>>>> move it but afraid my thumbs will rub off the lettering over time. >>>>>>>> It's this model: >>>>>>>> >>>>>>>> http://sliderulemuseum.com/SIC/C35_SIC_SINCO_250_1962.jpg >>>>>>>> >>>>>>>> Obviously the old "rub with a bar of soap" trick like on the linear >>>>>>>> ones doesn't work here. I also haven't tried any semi-destructive >>>>>>>> methods to pull it off. Any safe tricks to unstick it? >>>>>>> I can't tell from the photos. Does this have a single center wheel or >>>>>>> does the disc with the C scale ride on top of the one with the D scale >>>>>>> (the T scale wheel on the other side would be a separate smaller disc). >>>>>>> >>>>>>> If the single center wheel rides inside the outer wheel, can you tell >>>>>>> how the two are kept flat w.r.t. each other? If this was a straight >>>>>>> slide rule, it would be a tongue and groove, but I don't see how one >>>>>>> could assemble (let alone take apart) such a circular device. >>>>>>> >>>>>>> Looking at the trig side, I see what appears to be the end of what >>>>>>> could be a screw in the hub. There's a possibility that one could grab >>>>>>> each hub and unscrew them, allowing you to remove the cursor. In fact, >>>>>>> each side of the cursor is attached to its hub and by unscrewing the >>>>>>> spacer at the end, the center axle may be loose enough to unscrew by >>>>>>> manipulating the cusrsors (gently). But from there, it depends on how >>>>>>> the center and outer wheels are configured. >>>>>>> >>>>>> The center wheel is like an inlay but after Jim's hint I was able to >>>>>> gently pry it out. However, the thing looks a bit damaged inside, >>>>>> circular grinding marks, maybe from too much use or because the center >>>>>> has bulged up from the summer heat out here. Possibly the HP11C will >>>>>> outlive it. >>>>> Photos, Photos, Photos. Oh and some dimensional measurements might be >>>>> nice. >>>> http://www.analogconsultants.com/ng/images/sliderule1.JPG >>>> >>>> The center wheel that goes into the aluminum area is 2-3/8" in diameter, >>>> the whole thing is 3-1/4". >>>> >>> Forget my suggestion to iron the plastic part flat. With that insert, you >>> can't flatten it out properly and you'll just cause more problems. >>> >> Professor Hamann has responded and for the warped disk he suggested >> clamping it between two good sized aluminum plates and then immerse in >> hot water. He seems to be quite the expert on slide rules restoration. > > That might work. But you'll probably need to cut one out to fit your > center bushing. And I'd go a step further and machine a stud into one > plate to ensure that the disc cools with the bushing C/L held at right > angles. > > But its good to hear that my 'heat it up' technique isn't totally bogus. > It's just the center disk that's bulging up in the middle, the rest of the slide rule is straight. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Paul Hovnanian P.E. on 24 Feb 2010 20:21 Joerg wrote: > > Paul Hovnanian P.E. wrote: > > Joerg wrote: > >> Paul Hovnanian P.E. wrote: > >>> Joerg wrote: > >>> > >>>> JosephKK wrote: > >>>>> On Fri, 19 Feb 2010 18:51:53 -0800, Joerg <invalid(a)invalid.invalid> > >>>>> wrote: > >>>>> > >>>>>> Paul Hovnanian P.E. wrote: > >>>>>>> Joerg wrote: > >>>>>>>> Gents, > >>>>>>>> > >>>>>>>> My round slide rule is developing a sticky center wheel. I can still > >>>>>>>> move it but afraid my thumbs will rub off the lettering over time. > >>>>>>>> It's this model: > >>>>>>>> > >>>>>>>> http://sliderulemuseum.com/SIC/C35_SIC_SINCO_250_1962.jpg > >>>>>>>> > >>>>>>>> Obviously the old "rub with a bar of soap" trick like on the linear > >>>>>>>> ones doesn't work here. I also haven't tried any semi-destructive > >>>>>>>> methods to pull it off. Any safe tricks to unstick it? > >>>>>>> I can't tell from the photos. Does this have a single center wheel or > >>>>>>> does the disc with the C scale ride on top of the one with the D scale > >>>>>>> (the T scale wheel on the other side would be a separate smaller disc). > >>>>>>> > >>>>>>> If the single center wheel rides inside the outer wheel, can you tell > >>>>>>> how the two are kept flat w.r.t. each other? If this was a straight > >>>>>>> slide rule, it would be a tongue and groove, but I don't see how one > >>>>>>> could assemble (let alone take apart) such a circular device. > >>>>>>> > >>>>>>> Looking at the trig side, I see what appears to be the end of what > >>>>>>> could be a screw in the hub. There's a possibility that one could grab > >>>>>>> each hub and unscrew them, allowing you to remove the cursor. In fact, > >>>>>>> each side of the cursor is attached to its hub and by unscrewing the > >>>>>>> spacer at the end, the center axle may be loose enough to unscrew by > >>>>>>> manipulating the cusrsors (gently). But from there, it depends on how > >>>>>>> the center and outer wheels are configured. > >>>>>>> > >>>>>> The center wheel is like an inlay but after Jim's hint I was able to > >>>>>> gently pry it out. However, the thing looks a bit damaged inside, > >>>>>> circular grinding marks, maybe from too much use or because the center > >>>>>> has bulged up from the summer heat out here. Possibly the HP11C will > >>>>>> outlive it. > >>>>> Photos, Photos, Photos. Oh and some dimensional measurements might be > >>>>> nice. > >>>> http://www.analogconsultants.com/ng/images/sliderule1.JPG > >>>> > >>>> The center wheel that goes into the aluminum area is 2-3/8" in diameter, > >>>> the whole thing is 3-1/4". > >>>> > >>> Forget my suggestion to iron the plastic part flat. With that insert, you > >>> can't flatten it out properly and you'll just cause more problems. > >>> > >> Professor Hamann has responded and for the warped disk he suggested > >> clamping it between two good sized aluminum plates and then immerse in > >> hot water. He seems to be quite the expert on slide rules restoration. > > > > That might work. But you'll probably need to cut one out to fit your > > center bushing. And I'd go a step further and machine a stud into one > > plate to ensure that the disc cools with the bushing C/L held at right > > angles. > > > > But its good to hear that my 'heat it up' technique isn't totally bogus. > > > > It's just the center disk that's bulging up in the middle, the rest of > the slide rule is straight. So the periphery of that disk is dragging on the alumin(i)um part? Flattening it out might help, but that's going to be tricky with the center bushing. A thin washer that fits around the smaller diameter hub and lifts the center disk a few thousandths might help. And if you can find some Teflon stick on 'dots', you can put a few of these around the outer parts of the recess to keep the plastic disk from contacting the aluminum when you push it around. -- Paul Hovnanian mailto:Paul(a)Hovnanian.com ------------------------------------------------------------------ Experience is the worst teacher. It always gives the test first and the instruction afterward.
From: Joerg on 24 Feb 2010 21:18 Paul Hovnanian P.E. wrote: > Joerg wrote: >> Paul Hovnanian P.E. wrote: >>> Joerg wrote: >>>> Paul Hovnanian P.E. wrote: >>>>> Joerg wrote: >>>>> >>>>>> JosephKK wrote: >>>>>>> On Fri, 19 Feb 2010 18:51:53 -0800, Joerg <invalid(a)invalid.invalid> >>>>>>> wrote: >>>>>>> >>>>>>>> Paul Hovnanian P.E. wrote: >>>>>>>>> Joerg wrote: >>>>>>>>>> Gents, >>>>>>>>>> >>>>>>>>>> My round slide rule is developing a sticky center wheel. I can still >>>>>>>>>> move it but afraid my thumbs will rub off the lettering over time. >>>>>>>>>> It's this model: >>>>>>>>>> >>>>>>>>>> http://sliderulemuseum.com/SIC/C35_SIC_SINCO_250_1962.jpg >>>>>>>>>> >>>>>>>>>> Obviously the old "rub with a bar of soap" trick like on the linear >>>>>>>>>> ones doesn't work here. I also haven't tried any semi-destructive >>>>>>>>>> methods to pull it off. Any safe tricks to unstick it? >>>>>>>>> I can't tell from the photos. Does this have a single center wheel or >>>>>>>>> does the disc with the C scale ride on top of the one with the D scale >>>>>>>>> (the T scale wheel on the other side would be a separate smaller disc). >>>>>>>>> >>>>>>>>> If the single center wheel rides inside the outer wheel, can you tell >>>>>>>>> how the two are kept flat w.r.t. each other? If this was a straight >>>>>>>>> slide rule, it would be a tongue and groove, but I don't see how one >>>>>>>>> could assemble (let alone take apart) such a circular device. >>>>>>>>> >>>>>>>>> Looking at the trig side, I see what appears to be the end of what >>>>>>>>> could be a screw in the hub. There's a possibility that one could grab >>>>>>>>> each hub and unscrew them, allowing you to remove the cursor. In fact, >>>>>>>>> each side of the cursor is attached to its hub and by unscrewing the >>>>>>>>> spacer at the end, the center axle may be loose enough to unscrew by >>>>>>>>> manipulating the cusrsors (gently). But from there, it depends on how >>>>>>>>> the center and outer wheels are configured. >>>>>>>>> >>>>>>>> The center wheel is like an inlay but after Jim's hint I was able to >>>>>>>> gently pry it out. However, the thing looks a bit damaged inside, >>>>>>>> circular grinding marks, maybe from too much use or because the center >>>>>>>> has bulged up from the summer heat out here. Possibly the HP11C will >>>>>>>> outlive it. >>>>>>> Photos, Photos, Photos. Oh and some dimensional measurements might be >>>>>>> nice. >>>>>> http://www.analogconsultants.com/ng/images/sliderule1.JPG >>>>>> >>>>>> The center wheel that goes into the aluminum area is 2-3/8" in diameter, >>>>>> the whole thing is 3-1/4". >>>>>> >>>>> Forget my suggestion to iron the plastic part flat. With that insert, you >>>>> can't flatten it out properly and you'll just cause more problems. >>>>> >>>> Professor Hamann has responded and for the warped disk he suggested >>>> clamping it between two good sized aluminum plates and then immerse in >>>> hot water. He seems to be quite the expert on slide rules restoration. >>> That might work. But you'll probably need to cut one out to fit your >>> center bushing. And I'd go a step further and machine a stud into one >>> plate to ensure that the disc cools with the bushing C/L held at right >>> angles. >>> >>> But its good to hear that my 'heat it up' technique isn't totally bogus. >>> >> It's just the center disk that's bulging up in the middle, the rest of >> the slide rule is straight. > > So the periphery of that disk is dragging on the alumin(i)um part? > Flattening it out might help, but that's going to be tricky with the > center bushing. A thin washer that fits around the smaller diameter hub > and lifts the center disk a few thousandths might help. And if you can > find some Teflon stick on 'dots', you can put a few of these around the > outer parts of the recess to keep the plastic disk from contacting the > aluminum when you push it around. > You'd have to use the teflon because the center wheel is sorta floppy. The only way to move it is to press down on it with your thumbs. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: JosephKK on 24 Feb 2010 22:25 On Wed, 24 Feb 2010 12:50:04 -0800, Joerg <invalid(a)invalid.invalid> wrote: >JosephKK wrote: >> On Mon, 22 Feb 2010 13:21:01 -0800, Joerg <invalid(a)invalid.invalid> wrote: >> >>> JosephKK wrote: >>>> On Fri, 19 Feb 2010 18:51:53 -0800, Joerg <invalid(a)invalid.invalid> wrote: >>>> >>>>> Paul Hovnanian P.E. wrote: >>>>>> Joerg wrote: >>>>>>> Gents, >>>>>>> >>>>>>> My round slide rule is developing a sticky center wheel. I can still >>>>>>> move it but afraid my thumbs will rub off the lettering over time. It's >>>>>>> this model: >>>>>>> >>>>>>> http://sliderulemuseum.com/SIC/C35_SIC_SINCO_250_1962.jpg >>>>>>> >>>>>>> Obviously the old "rub with a bar of soap" trick like on the linear ones >>>>>>> doesn't work here. I also haven't tried any semi-destructive methods to >>>>>>> pull it off. Any safe tricks to unstick it? >>>>>> I can't tell from the photos. Does this have a single center wheel or >>>>>> does the disc with the C scale ride on top of the one with the D scale >>>>>> (the T scale wheel on the other side would be a separate smaller disc). >>>>>> >>>>>> If the single center wheel rides inside the outer wheel, can you tell >>>>>> how the two are kept flat w.r.t. each other? If this was a straight >>>>>> slide rule, it would be a tongue and groove, but I don't see how one >>>>>> could assemble (let alone take apart) such a circular device. >>>>>> >>>>>> Looking at the trig side, I see what appears to be the end of what could >>>>>> be a screw in the hub. There's a possibility that one could grab each >>>>>> hub and unscrew them, allowing you to remove the cursor. In fact, each >>>>>> side of the cursor is attached to its hub and by unscrewing the spacer >>>>>> at the end, the center axle may be loose enough to unscrew by >>>>>> manipulating the cusrsors (gently). But from there, it depends on how >>>>>> the center and outer wheels are configured. >>>>>> >>>>> The center wheel is like an inlay but after Jim's hint I was able to >>>>> gently pry it out. However, the thing looks a bit damaged inside, >>>>> circular grinding marks, maybe from too much use or because the center >>>>> has bulged up from the summer heat out here. Possibly the HP11C will >>>>> outlive it. >>>> Photos, Photos, Photos. Oh and some dimensional measurements might be nice. >>> >>> http://www.analogconsultants.com/ng/images/sliderule1.JPG >>> >>> The center wheel that goes into the aluminum area is 2-3/8" in diameter, >>> the whole thing is 3-1/4". >> >> There is some useful dimensional things going on there that are not >> showing up in that photo. Could you tip them to about 75 degrees and >> take another shot? Could you measure the dimensions of all the brass >> pieces and the thickness' of the disk parts? > > >Took the calipers to it: > >The aluminum base is 0.022" thick, the recess for the center disk (and >thus the thickness of the outer plastic ring) is 0.051", the rotating >inner disk is 0.040" thick so has some wiggle room for an underlayment. >Even up to 0.018" (minus some clearance) because the brass center hub >sticks out 0.058" above the aluminum surface. Thank you, a 0.003" PTFE (or maybe the right variation of PET (nylon) or polyethylene) washer will work wonders. Especially if assisted by silicone lubricant film applied to the aluminum as liquid or spray. Now if i just knew where to get it, try TAP plastics though.
From: Joerg on 25 Feb 2010 12:38
JosephKK wrote: > On Wed, 24 Feb 2010 12:50:04 -0800, Joerg <invalid(a)invalid.invalid> wrote: > >> JosephKK wrote: >>> On Mon, 22 Feb 2010 13:21:01 -0800, Joerg <invalid(a)invalid.invalid> wrote: >>> >>>> JosephKK wrote: [...] >>>>> Photos, Photos, Photos. Oh and some dimensional measurements might be nice. >>>> http://www.analogconsultants.com/ng/images/sliderule1.JPG >>>> >>>> The center wheel that goes into the aluminum area is 2-3/8" in diameter, >>>> the whole thing is 3-1/4". >>> There is some useful dimensional things going on there that are not >>> showing up in that photo. Could you tip them to about 75 degrees and >>> take another shot? Could you measure the dimensions of all the brass >>> pieces and the thickness' of the disk parts? >> >> Took the calipers to it: >> >> The aluminum base is 0.022" thick, the recess for the center disk (and >> thus the thickness of the outer plastic ring) is 0.051", the rotating >> inner disk is 0.040" thick so has some wiggle room for an underlayment. >> Even up to 0.018" (minus some clearance) because the brass center hub >> sticks out 0.058" above the aluminum surface. > > Thank you, a 0.003" PTFE (or maybe the right variation of PET (nylon) or > polyethylene) washer will work wonders. Especially if assisted by silicone > lubricant film applied to the aluminum as liquid or spray. Now if i just > knew where to get it, try TAP plastics though. Yep, have to get to a TAP outlet soon. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |