Sourcing mechanical components

[AncientBrit]

The only mechanical NBTV devices I've constructed have been the MUTR kit and my Nipkow disc camera.
Both these used a direct drive from a small cassette motor to the disc.

I'd like to construct a drum monitor say 250mm in diameter.

I suspect that I'll need a more powerful motor and some form of gearing.
I want to steer clear of a mains powered motor for safety and control reasons so it'll probably have to be a 12 or 18v dc motor.

I'm looking for a bit of guidance here from the more mechanical members of this forum who've "been there, done that"
I only have access only to power tools, but no lathe, so any modifications will have to be simple (and robust).

I've tried "harvesting" components from a few printers but the motors and gears are very lightweight and I don't think will be up to the job.

So:
Size of motor?
Gears or belt drive?
Toothed belt or V belt?
Ratios?
Construction of drum? (single spiral at this stage)
Bearings and shafts to suit gears/pulleys?

And finally sourcing the components.
I'm prepared to buy new as long as the total cost is reasonable, say 30 GBP.
So additionally if any UK members can suggest a UK source that would be helpful.


Cheers,

Graham

[Viewmaster]

Graham, I have never made a drum monitor so 'haven't been there, done it', but for small toothed belts/pulleys etc try HPC gears.

I have used their toothed belts on some projects but the problem is the they are pricey but they do have a huge range of sizes.
http://www.hpcgears.com/

For aluminium/brass/steel rod/sheet just search ebay and compare prices.
I also use Mr Holt's 'Kirjeng' services for odds and ends.......taps/ brass/ali/plastic rod etc. No website but email him for his catalogue. Not a big range but cheapish.

tandsholtatkirjeng @ btinternet.com (close the anti spam gaps at @)

I have used this list of suppliers too, when looking for materials.......
http://www.modeleng.org/supply.htm

Some robot web site suppliers list parts/motors that might be useful......just google.

That's my 2P's worth, Graham.........
....now you only have £29.98 left to spend.

added......don't forget to search this forum for 'drum monitors.' and similar
words.

[Harry Dalek]

Yes i think for parts always think out side the box and if it doesn't work arr chuck it try again no one will know


Only time i used gears for nbtv was the only time ! i went right to pulley system the drum acted like a passive amplifier mine was a home made knock up so a nice designed gear box might help things.

For the drum as again i have worked out from mistakes it needs to be as rigid as you can get for what you want it to do or as my last one i got wobble on my raster lines at higher speeds.

Really interested to see what you make Graham with your electronic skills it will be a fine monitor .

[AncientBrit]

Thanks Harry, Albert,

EDIT.
The trouble is you "mechanical guys" make it look so easy !

Regards,

Graham

[Viewmaster]

Thanks Harry, Albert,

EDIT.
The trouble is you "mechanical guys" make it look so easy !
Graham

Ah, if only I found the electronics easy.

One thing for sure, you will need a good bearing for the mirror drum to quietly rotate on without wobble. Old video recorders and ball races spring to mind.
A ball race doesn't have to be pushed into a tight fit housing where a lathe is required.

Although I was initially trained as a toolmaker I am a great bodge engineer.
For ball races, in the past, I have just put 3 screws and bolts spaced around the outside to bolt the ball race down on to a flat surface.
2 races mounted opposite each other with a shaft running through makes a good bearing/shaft system.

No lathe etc requiired. Just a drill and 3 nuts and bolts for each bearing.

I once made a 12 inch dia worm wheel for a telescope, out of a picador pulley with 3/8 BSF threaded rod pulled around the 'V' groove and pinned in.
Another sprung loaded threaded rod mounted at a slight angle formed the rotating worm.

Engineering is difficult without machine tools, bodge engineering isn't.

I'm sure Harry and I and others too will help you with suggestions as you get going on your drum. Good luck.

[AncientBrit]

Thanks again Albert,

Much appreciated,

Cheers,

Graham

[Viewmaster]

Just to inspire you here are some piccys of club member's drums.

[AncientBrit]

Thanks Albert.

I think for simplicity I'll go for an aperture drum rather than a mirror drum.

I note the use of a simple belt and pulley gearing as well.

Regards,

Graham

[Steve Anderson]

For a rather eclectic mix of electronic and mechanical suppliers including tools, this may be worth a look...

Skim past the blurb at the top r.e. R.S, Farnell etc...

http://www.ifwtech.co.uk/g3sek/in-prac/components.htm

Steve A.

[Viewmaster]

Thanks Albert.

I think for simplicity I'll go for an aperture drum rather than a mirror drum.
I note the use of a simple belt and pulley gearing as well.

O dear, I got hold of the wrong end of the stick, thinking of mirror drum instead of aperture.
There's some good threads and picture of aperture drums if you search for all terms, 'aperture drum.' on this forum.

..........One idea was to use a hampster to rotate the drum or use a washing machine drum ...."It cleans as it screens."

[Steve Anderson]

..or use a washing machine drum ...."It cleans as it screens." :)

One of my odd ideas I think...as these things are electronically regulated it's not as daft as it may seem, whatever, using elements from a washing machine you're bound to end up with nice clean pictures...and the OMO, DAZ and Persil commercials should look spectacular!! Though I do decline to comment on "Mild Green Fairy Liquid"....

Steve A.

[DrZarkov]

For bearings, motors, rotating mirrors and wheels old laserprinters are a good source of material.
For fitting Nipkow discs I use connector for propellors made for model-planes: http://www.conrad.de/ce/de/product/2056 ... bs_technik

[AncientBrit]

There's some very good ideas there gents.
Thanks for spending the time replying.

Must admit Dr.Z I had not thought about model aircraft.
Another of your hobbies maybe?

(As for the hamster I'm afraid he met a nasty end in the washing machine)

Kind regards,

Graham

[DrZarkov]

No, model aircraft is not another hobby of me. But in the village where I lived before we had a model aircraft shop which was also the post-office for the "Hermes Parcel Service". There I saw the motors (brushless, powerful high quality motors BTW, very good suitable for heavy scanners like drums or mirrorscrews!) and the connectors for the propellers. On Saturday in Loughborough I will show a Televisor with such a connector.

[gary]

BTW, since the good doctor mentioned the brushless R/C motors - I recently purchased one (they are available quite reasonably priced now) specifically to ascertain if they are suitable for NBTV use.

The thing that attracts me to them is that they are effectively *synchronous* motors. (inexpensive synchronous motors being a kind of "holy grail" to NBTV experimenters).

It remains to be seen whether they can be operated at the comparatively low speed of 750 RPM if directly coupled, or of that order indirectly coupled.