I have many cases where I need to minimise the friction between two tightly-fitting concentric cardboard cylinders. What is the best way to do this? Baby powder? Graphite powder? Impregnating one side with plastic and sanding with fine sandpaper (impregnating two sides isn’t allowed) – if so which plastic?

I tried sanding the cardboard without success – that just loosens the surface fibres which increases the friction. Also, cutting the cardboard surface off isn’t an option as I need a snug fit.

Interesting question.

I’ve applied talcum powder to playing cards to make them slip better. Particularly those tourist souvenir type cards.

On a different note, I’ve made a very smooth surface on thin plywood by applying successive coats ceiling white paint and then sanding bank with very very fine sandpaper in between each coat. I’ve only done it on flat surfaces of plywood, not sure if it would work on cardboard rolls.

mollwollfumble said:

I have many cases where I need to minimise the friction between two tightly-fitting concentric cardboard cylinders. What is the best way to do this? Baby powder? Graphite powder? Impregnating one side with plastic and sanding with fine sandpaper (impregnating two sides isn’t allowed) – if so which plastic?

I tried sanding the cardboard without success – that just loosens the surface fibres which increases the friction. Also, cutting the cardboard surface off isn’t an option as I need a snug fit.

Gladwrap.

glad wrap is sticky.

party_pants said:

glad wrap is sticky.

Glad wrap on one. The other left as cardboard. I suspect that would roll.

I vaguely remember something called Molyslip or similar, supposed to stop friction.

Look up Molybdenum disulphide, that’s what I was thinking of.

polytetrafluoroethylene

Yeah, PTFE (Teflon spray) would have to be worth a try. Locksmiths around here use it instead of Graphite.

FWIW, Trombone players traditionally use Nivea Hand Cream on the slide and frequently apply water in a mist from a small spray bottle.

Two things, if it’s what I think it’s for ….
- Perhaps try putting a very small cone angle into the tubes, so when they are engaged they are quite firm but as soon as they start to separate they get loose quickly. Only 0.5° to 1° would be needed.
- For when the staging charge goes off, perhaps try putting a small cut (to about half or so the cardboard depth) into the outer tube so it gets blows-out and releases its grip on the inner cardboard tube.

I was going to say PTFE

I was thinking that I had no opportunity to test options, but now I realise I have enough spare materials for three friction tests.

> Glad wrap on one.

I’m keeping that in mind for later. I was thinking of getting some wrapping paper and then using the free plastic sleeve it comes in to shrink-wrap around the outside, but too thick in this case and i’m worried about crumpling distortion..

> Molyslip or similar, Molybdenum disulphide

Will search out.

> polytetrafluoroethylene. PTFE (Teflon spray) would have to be worth a try. Locksmiths around here use it instead of Graphite.

I didn’t know that about locksmiths – had tried graphite on locks ages ago with the undesirable result that the key kept coming out black and transferring the black to my hands.

> FWIW, Trombone players traditionally use Nivea Hand Cream on the slide and frequently apply water in a mist from a small spray bottle.

Excellent idea. I was considering perhaps soft soap, margarine or grease, but hand cream would be better.

> Perhaps try putting a very small cone angle into the tubes, so when they are engaged they are quite firm but as soon as they start to separate they get loose quickly. Only 0.5° to 1° would be needed.

Part of my problem is that the inner cardboard tube comes with a small taper inbuilt into it, averaging 0.2° in the WRONG direction, which is a serious pest. Later, if I switch to an aluminium or plastic outer tube I could fix that, but not yet.

> Glad wrap on one.

I’m keeping that in mind for later. I was thinking of getting some wrapping paper and then using the free plastic sleeve it comes in to shrink-wrap around the outside, but too thick in this case and i’m worried about crumpling distortion..
——————-
I thnik baking paper or teflon lining paper would be better than glad wrap.

Teflon sounds good.

I suppose Gladwrap is worth a try, but it may come loose & get wrinkly. You can stop Gladwrap from sticking to Gladwrap by coating it with talcum powder.

OTOH, Gladwrap may not behave nicely if it gets hot.

Try not to use cardboard ?

wookiemeister said:

Try not to use cardboard ?

wookeimeister might remember my earlier posted question about thin-wall tubes. Was able to get cardboard thin-wall, but not yet plastic or aluminium. Plastic or aluminium would be preferred.

> FWIW, Trombone players traditionally use Nivea Hand Cream on the slide and frequently apply water in a mist from a small spray bottle.

Looks like those trombonists may be on to something. I set up a friction test rig apparatus using corrugated cardboard cut to size as specimens, a fishing sinker for weight, and a bulldog clip holding elastic thread for measuring the transverse force applied. Friction coefficients so far from best to worst:
0.33 HTB grease
0.41 Nivea soft
0.50 Bare cardboard
0.51 Talc
0.53 Motor oil
0.58 Body lotion
0.60 Skin repair cream
0.76 Personal lubricant.

So, so far, only two have been better than bare cardboard, the grease and the Nivea. Haven’t tried PTFE or molybdenum disulphide yet.

molybdenum disulphide

good grease but you’ll get it everywhere.

JudgeMental said:

good grease but you’ll get it everywhere.

Not everywhere, not anywhere. Let me know if you can find a place that sells grease with NGLI = 0 or 1, standard grease has NGLI = 2 but I want something slightly less viscous.

Bought some PTFE spray, graphite powder and Silicone lubricant spray, the last because it claims to lubricate both rubber and wood, which is as close to cardboard as I’ve seen. Total waste of money.

Friction coefficients from best to worst:
0.33 HTB grease
0.41 Nivea soft
0.46 Graphite powder
0.50 Bare cardboard
0.51 Talc
0.53 Motor oil
0.58 PTFE spray
0.58 Body lotion
0.60 Skin repair cream
0.61 Silicone lubricant spray
0.76 Personal lubricant.

i meant that when you use it a little bit seems to multiply.

Caterpillar make a spray-film dry lubricant. It has graphite and molybdenum disulphide in a quick-setting resin.

I wonder whether the notion of the joint containing a heat-shrinkable plastic layer is sensible? When the middle layer gets hot, it shrinks the inner cardboard tube, allowing it to be ejected.

Considerd polishing cardboard with Cerium Oxide ?
Powdered nylon as lube?

> Caterpillar make a spray-film dry lubricant. It has graphite and molybdenum disulphide in a quick-setting resin.

> I wonder whether the notion of the joint containing a heat-shrinkable plastic layer is sensible? When the middle layer gets hot, it shrinks the inner cardboard tube, allowing it to be ejected.

Too thick. Even 0.1 mm thick would be too thick here. I accidentally got spray paint in one of the gaps and after it dried they wouldn’t fit together at all.

> Considerd polishing cardboard with Cerium Oxide ? Powdered nylon as lube?

I tried some SAE 90 gear oil, as intermediate in viscosity between grease and motor oil, but no better than plain cardboard. Coefficient of friction still 0.5.