panning timelapse head - 2 axis

Plugsocket:
at £15 a piece.. or am I just being a cheapskate?
RS is not renowned for cheap as it's more geared (no pun intended) toward business instead of consumer. You can get cheaper stuff but they give no details of worm pitch to calculate the reduction. Maybe eBay would do stuff like this.

on the note of working out gear ratios I'm getting into a bit of a muddle...
so I need a 90 tooth gear to achieve a 0.5 degree rotation per step? am I right or am I crazy?
I work it out at 1.416 degree per step using a 17:90 ratio. To get a 0.5 degree per step you would need a 17:255 ratio.

You can achieve massive gearing reductions in a small space using epicyclic gearboxes, and they also package well because they are self contained and have co-axial input and output shafts.

This could be just what you're looking for. It's easy to connect to Arduino.

This could be just what you're looking for. It's easy to connect to Arduino.

Does it have positional feedback?

sbright33:
This could be just what you're looking for. It's easy to connect to Arduino.

http://www.amazon.com/Bescor-MP101-Video-Motorized-Head/dp/B0000AUR21

I've seen these, I wan't to make my own for the hell of it and it'll probably work out cheaper.

Riva:

Plugsocket:
at £15 a piece.. or am I just being a cheapskate?
RS is not renowned for cheap as it's more geared (no pun intended) toward business instead of consumer. You can get cheaper stuff but they give no details of worm pitch to calculate the reduction. Maybe eBay would do stuff like this.

on the note of working out gear ratios I'm getting into a bit of a muddle...
so I need a 90 tooth gear to achieve a 0.5 degree rotation per step? am I right or am I crazy?
I work it out at 1.416 degree per step using a 17:90 ratio. To get a 0.5 degree per step you would need a 17:255 ratio.

Of Course you are correct! I understand now

stepper angle / output gear angle and then multiply by the output gear teeth.

This is a problem. If I invested in a 1.8 degree stepper I would only need a 17:61 reduction.

I ideally want to keep the design as simplistic as possible, so it is robust and wont fail easily in the field.

Worm gears are a strong possibility.. Just need to find some a little bit cheaper with the sizes specified!

Yeah the worm gear pricing has shocked me a couple of times and I too would like to find a reliable source of less expensive worm gears.

Keep in mind: the cheaper you go, the more likely it is to fail in the field...

Bescor. It does not know it's current position unless it's at the end stop. I ripped out the internal mechanical stop, and made a dowel that can be removed to allow for continuous rotation. Starting from the end, you can move for x seconds, at y speed, and you'll be at the same angle every time. The speed is determined by the DC voltage to the motor. So there is no way to predict how fast V volts will be. It is not a stepper motor. But it is mechanically sturdy to support a large DSLR and long lens. Perfect for GigalPixel photography using the end stop for the edge of each each row.

aarondc:
Yeah the worm gear pricing has shocked me a couple of times and I too would like to find a reliable source of less expensive worm gears.

Keep in mind: the cheaper you go, the more likely it is to fail in the field...
[/quote]

I'm going to a shop later today that might be ale to order a set in its plastic though so I'll reject it if I think it's not going to be man enough.

I've seen a rig use the metal worm gears, I guess I may have to just pay the price as I don't really want problems with gears while it's in the field.

aarondc:
Yeah the worm gear pricing has shocked me a couple of times and I too would like to find a reliable source of less expensive worm gears.
Keep in mind: the cheaper you go, the more likely it is to fail in the field...

In reply #20 I did post a cheaper alternative I found, £2.69 for a worm and a 40 tooth gear. The site has zero information like worm pitch so you cannot work out the ratios. eBay also has some stuff but they are all plastic so may not last as long as you hope.

Plugsocket:

Riva:

Plugsocket:
at £15 a piece.. or am I just being a cheapskate?
RS is not renowned for cheap as it's more geared (no pun intended) toward business instead of consumer. You can get cheaper stuff but they give no details of worm pitch to calculate the reduction. Maybe eBay would do stuff like this.

on the note of working out gear ratios I'm getting into a bit of a muddle...
so I need a 90 tooth gear to achieve a 0.5 degree rotation per step? am I right or am I crazy?
I work it out at 1.416 degree per step using a 17:90 ratio. To get a 0.5 degree per step you would need a 17:255 ratio.

Not sure where you are upto yet with this ? Sparkfun have a module call the EasyDriver which is specifically designed to drive stepper motors - they also have a number of small grunty stepper motors that match up well.

In terms of gearing the motors etc - have a look at Meccano pieces - i have "borrowed" heaps of my sons stuff for various projects that i put together - dirt cheap and lots of options.

Craig

Of Course you are correct! I understand now

stepper angle / output gear angle and then multiply by the output gear teeth.

This is a problem. If I invested in a 1.8 degree stepper I would only need a 17:61 reduction.

I ideally want to keep the design as simplistic as possible, so it is robust and wont fail easily in the field.

Worm gears are a strong possibility.. Just need to find some a little bit cheaper with the sizes specified!

Riva:

aarondc:
Yeah the worm gear pricing has shocked me a couple of times and I too would like to find a reliable source of less expensive worm gears.
Keep in mind: the cheaper you go, the more likely it is to fail in the field...

In reply #20 I did post a cheaper alternative I found, £2.69 for a worm and a 40 tooth gear. The site has zero information like worm pitch so you cannot work out the ratios. eBay also has some stuff but they are all plastic so may not last as long as you hope.

Yeah it seems that metal is the way to go I think. Just need to find an affordable one.

Why would I need the pitching to work out the ratio of the worm gear?

I always assumed the worm gear = 1 tooth

Plugsocket:
Why would I need the pitching to work out the ratio of the worm gear?

I always assumed the worm gear = 1 tooth

True, bad terminology on my behalf what I should have said was 'the number of starts' as this will effect the ratio if it's >1

craigcurtin:
Not sure where you are upto yet with this ? Sparkfun have a module call the EasyDriver which is specifically designed to drive stepper motors - they also have a number of small grunty stepper motors that match up well.

In terms of gearing the motors etc - have a look at Meccano pieces - i have "borrowed" heaps of my sons stuff for various projects that i put together - dirt cheap and lots of options.

Craig

At the minute all I have on the way is:

  • Arduino UNO (arrived)
  • Adafruit motor driver

I've found this mecano worm gear.. it looks single start to me I can't see why you would need multiple starts on a mecano contraption..

http://meccanoman.co.uk/catalog/product_info.php?products_id=1163&osCsid=9f9fb2a1d8e5f27be390a614cecf6000

and a 30 tooth to go with it.. it is a different thickness to the worm gear though this shouldn't matter should it?
http://meccanoman.co.uk/catalog/product_info.php?cPath=1_14_15&products_id=1098&osCsid=9f9fb2a1d8e5f27be390a614cecf6000

I think the pitch has to match.

Their checkout is closed till September? Huh!?

aarondc:
Their checkout is closed till September? Huh!?

haha I think I need to go to specsavers.. :.

I'll keep looking...but I dont think you can get a mecano set just the worm and gear sperately so I assume the pitches would match?

found some mecano gears that I think will work.. according to another spares website worm gear 32 will mesh with gear 27a which is a 57 tooth...

http://www.ebay.co.uk/itm/MECCANO-PART-NO-27A-GEAR-WHEEL-DOUBLE-TAPPED-POST-WAR-/390621560183?pt=UK_Construction_Toys_Kits&hash=item5af2dbfd77

http://www.ebay.co.uk/itm/Meccano-Worm-Gear-part-32-/250916785356?pt=UK_Construction_Toys_Kits&hash=item3a6bce4ccc

Plugsocket:
found some mecano gears that I think will work.. according to another spares website worm gear 32 will mesh with gear 27a which is a 57 tooth...

http://www.ebay.co.uk/itm/MECCANO-PART-NO-27A-GEAR-WHEEL-DOUBLE-TAPPED-POST-WAR-/390621560183?pt=UK_Construction_Toys_Kits&hash=item5af2dbfd77

http://www.ebay.co.uk/itm/Meccano-Worm-Gear-part-32-/250916785356?pt=UK_Construction_Toys_Kits&hash=item3a6bce4ccc

The good thing about them as well is there is so much metal in the boss that you can drill it out to match your motor shaft precisely and the price is outstanding. Used to love playing with it when i was a kid and bought a couple of sets for my son as well.

Craig

Just an update with this..

got the motorshield hooked up to the arduino and the mecanno gears are here.

I'm just waiting for the battery to arrive and I can start experimenting,I need to know if the motor will be able to hold the weight of the camera tilting on the spec sheet it gives the holding torque at 39.2Nm but that doesn't really mean much to me so I'll just try it.. once I've got everything running I'll set about fabricating the head :slight_smile: