Gina's Observatory Roll-Off-Roof Automation

[mckinnell]

Gina, i have very very bad BP problems, a very good food is PORRIDGE, a great gift from us Scots, ha ha ha, you need a lot of salt to sugar and it DOES help with BP, if you can as we say, ! Tak the porridge ye ken!, give it a go.

 

                                                                                                              All my very best,                    Tom.

[Gina]

I eat a large bowl of porridge for my breakfast every morning.  I swear by it.

[Rusted]

2 minutes ago, Gina said:

I eat a large bowl of porridge for my breakfast every morning.  I swear by it.

Brain food. We call it "Organic Muesli" because we're posh.  

[Gina]

Still feeling tired at present - may not do anything today.  I have been known to recover in the evening though...

[Gina]

Had an invitation to a party at a neighbours' house which went on most of the evening.  We all had a great time.  I shall not be doing any imaging tonight - the moon was bright enough to see by!  Which was just as well as I expected to be back well before dark and didn't take a torch...

[Gina]

Heavy showers this afternoon so nothing doing in the observatory.  I might be able to do some more on the electronics though.

[Gina]

Been clearing some stuff to get to my little Chinese lathe.

[Rusted]

Sorry, wrong time of year, Madam. You can't be doing spring cleaning out of season!
God knows I've tried and it just doesn't work. 

Jobsworth

[Gina]

I can assure you Sir, that I am not cleaning any springs!  😄

[Gina]

I do have a problem with my lathe though.  The layshaft timing pulley is broken and I've been hunting for a spare.  The lathe is one of those little cheapo Chinese jobs, this one badged Warco and called "Variable Speed, Super Mini lathe".  I had this problem early on and designed and printed replacements in plastic which, of course, didn't last very long.  I think the original was plastic.  The pulley has 31 teeth, is 45mm OD, 10mm wide, with a 10mm bore with keyway.  If I could source a metal one I might be able to keep the lathe running for more than a few days at a time.  Anyone have any ideas or suggestions.  (Buying a "proper" lathe will not be accepted as it's way out of my price range!)

[Davey-T]

With all the budding machinists on this site there must be someone that could knock one up out of something more substantial than plastic 

Dave

[JamesF]

3 minutes ago, Gina said:

I do have a problem with my lathe though.  The layshaft timing pulley is broken and I've been hunting for a spare.  The lathe is one of those little cheapo Chinese jobs, this one badged Warco and called "Variable Speed, Super Mini lathe".  I had this problem early on and designed and printed replacements in plastic which, of course, didn't last very long.  I think the original was plastic.  The pulley has 31 teeth, is 45mm OD, 10mm wide, with a 10mm bore with keyway.  If I could source a metal one I might be able to keep the lathe running for more than a few days at a time.  Anyone have any ideas or suggestions.  (Buying a "proper" lathe will not be accepted as it's way out of my price range!)

There are a number of UK vendors of the same basic lathe -- different colours, slightly different setup, but basically the same lathe.  Some of them sell sets of metal gears to replace the plastic ones.  I think Axminster's C2-300 is the same.  Chester Machine Tools used to sell one, but it looks like they're trying to get out of the hobbyist market.  Arc Eurotrade are another.

Here might be a good place to start looking?  https://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/Lathes/SIEG-C3-SC2-SC3-Mini-Lathes/C3-SC2-SC3-Mini-Lathe-Upgrades

James

[Gina]

ArcEuroTrade was the first place I looked as I have bought spares from them before.

[Gina]

After more searching of AET I've found the plastic timing pulleys - I'll get two - only £4 each.  Now I want a replacement key as I can't find the old one.

[Gina]

Found the keys £0.68 so I'll get 5 as I'm always losing little things!  If I'm careful, I may yet have a usable lathe for non-precision items.  Actually, I've discovered the our new neighbours have a Myford lathe so for anything too big or too precision for my little heap I may have an alternative.  He doesn't have a 3D printer so some trading may occur in the future 😄

[Gina]

Lathe spares ordered - total £14.07 - makes more sense that trying to print parts!!  They may use stronger plastic - possibly.  No sign of metal replacements for the timing pulleys, only change wheel sets.  Maybe they consider the timing gears sacrificial in case of a serious overload..

[Gina]

I have a disc of what I think is Acetal, same as I used for the large pulley - 150mm OD x 20mm thick with a 12mm centre hole.  I have a 12mm SS bolt it could run on or possibly be turned to take a ball bearing.  The outside can be turned to provide a square bottom groove to take the chain.  It probably doesn't want to be quite as big as the large pulley and I can turn as much or as little from the outer edge.  Cutting the groove would reduce the diameter the chain runs on by half an inch radius, reducing the effective diameter from 6" to 5".  I might provide the groove with a chamfer for guiding the chain in better.  That would reduce the effective diameter by another half inch.

[Gina]

On looking up the properties of Acetal online I see it has a self-lubricating property and is even used in bearings so it would seem that just running on a smooth SS bolt should be alright.

[Gina]

I shall wait until I have the new smaller chain pulley made before replacing the motor unit on its baseboard.  I've scribbled on the pic of the motor drive to show the new pulley and chain run to the spring.

[Gina]

The larger pulley and original smaller pulley both have a ball bearing and I think I would prefer to have a ball bearing for the new pulley too.  A bit more work but not impossible.

[Gina]

I think a pair of ball bearings might be better than a single big one.  I could use skateboard bearings or I have several a bit bigger also sealed.  Skateboard bearings would be well up to the job.

[Gina]

The lathe parts were sent off yesterday by Royal Mail.  They haven't arrived in the post this morning so they should arrive tomorrow.  It'll be good to have the lathe working as 3D printing isn't perfect for everything!

[Gina]

Decided to bring the motor unit indoors and take off all the unused bits one of which was a spring pressing on the chain which only added extra friction in this application and made it difficult to feed the chain through.

Edited August 13, 2019 by Gina
typos

[Gina]

Just had a very heavy shower and now down to a drizzle.  Not much I can do in the observatory anyway until I get the lathe working and the smaller chain pulley made but I can look at the electronics.  I'll start again with the block diagram.

A lot of the connections are already decided leaving the actual Arduino pins to be decided and the interconnections to the RPi.

Taking the RPi first, signals from RPi to Nano comprise Open, Close and Abort.  Inputs to the RPi would be limit switches (Open, Closed) and motor current status (Normal, Overload).

[Rusted]

I hope you realise that the moment you connect the Rain Detector the entire world will  become drought ridden and bring an end to synchronized swimming as we know it?

Or something like that.  I have been putting off connecting my wireless rain gauge to my Ventus weather station for very similar reasons.

Good Luck!

Great Uncle Noah and the All-Sparks Synchronized Swimming Team