Model Boat Mayhem - Forum

Technical, Techniques, Hints, and Tips => DC Motors (Brushed) and Speed Controllers => Topic started by: cwmitch on September 06, 2018, 08:01:25 PM

Title: Motors in a 1/128th Hardy
Post by: cwmitch on September 06, 2018, 08:01:25 PM


Evening, I wonder if anyone can help I already had a pair of Graupner speed 400's
which I thought would be fine, But they seem a very tight squeeze. I then bought a
pair of Graupner speed 250's which fit fine but seem tiny, Do you think they will spin
M4 prop shafts and 25mm screws?




Double post as I firstly put this in Warships R&D, Before seeing this section.




Cheers Colin

Title: Re: Motors in a 1/128th Hardy
Post by: malcolmfrary on September 06, 2018, 08:17:49 PM
Assuming the 1935 one (there have been a LOT of HMS Hardys), the speed 250s should give the power needed on 2S or 6NiMH, but would probably be happier with smaller, or more lightly pitched, props.  The shaft size makes zero difference, it is the prop trying to turn power into moving water that does the work.
If the 1943 one, probably not enough power.
If the 1953 one, too many motors.
Title: Re: Motors in a 1/128th Hardy
Post by: raflaunches on September 06, 2018, 08:19:29 PM

Hi Colin

Personally I would change the prop shaft size for a M2 as it'll be more scale for a start. If you've already got the props you can get adaptors to change from M2 to a M4.
Hope this helps. :-))
Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on September 06, 2018, 08:23:49 PM
Sorry yes the 1935 H class Destroyer, I haven't got the running gear yet, George Sitek is making it
for me at the moment .
Title: Re: Motors in a 1/128th Hardy
Post by: Onetenor on September 23, 2018, 12:31:14 AM

Evening, I wonder if anyone can help I already had a pair of Graupner speed 400's
which I thought would be fine, But they seem a very tight squeeze. I then bought a
pair of Graupner speed 250's which fit fine but seem tiny, Do you think they will spin
M4 prop shafts and 25mm screws?

Why not fit Graupner 300 speed motors. Should be very good for scale plus a bit more. John



Double post as I firstly put this in Warships R&D, Before seeing this section.




Cheers Colin
Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on September 24, 2018, 08:12:19 AM
If I could find 300 speed motors I'd have a go, It seems everywhere I look
are sold out. Are Graupner doing away with the smaller brushed motors?






Colin.
Title: Re: Motors in a 1/128th Hardy
Post by: grendel on September 24, 2018, 08:22:37 AM
have you tried MFA directly for the motors - https://www.mfacomodrills.com/motors/380.html
Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on September 24, 2018, 08:43:25 AM
Unfortunately because of space limitations the MFA 380 motors are as large as the speed
400's I have already. And I'm finding them a very tight squeeze.




Colin.
Title: Re: Motors in a 1/128th Hardy
Post by: Tug Fanatic on September 24, 2018, 08:59:44 AM
I am guessing that your problem is beam rather than length of which you seem to have plenty. Is staggering the motors a possibility? 
Title: Re: Motors in a 1/128th Hardy
Post by: raflaunches on September 24, 2018, 09:48:01 AM
My Dad staggered his motors in his HMS X1 submarine as the car heater motors were too wide to sit side by side. It didnít create any problems with ballasting or listing.
Title: Re: Motors in a 1/128th Hardy
Post by: malcolmfrary on September 24, 2018, 09:49:53 AM
Staggering the motors with the forward one working through an extended U/J (much like happened in the real thing) is one solution.  280 size motors ( = speed 300 ) gives smaller diameter motors assuming that you can find the right voltage.  Is there a good reason for restricting the search to motors carrying a Graupner label?
Title: Re: Motors in a 1/128th Hardy
Post by: Tug Fanatic on September 24, 2018, 09:54:40 AM

Staggering the motors would not create any problems with ballast or list as it would weigh the same and the two motors could be set equal distance from the centre line.


Why would you need an extended U/J? Just use two propshafts of different lengths.
Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on September 24, 2018, 09:56:42 AM
No not particularly limiting myself to Graupner it's just what I had sitting around.
I'll do some investigating re staggering the motors that may be the way I need to go.




Thanks so much for your thoughts and suggestions.






Colin.
Title: Re: Motors in a 1/128th Hardy
Post by: malcolmfrary on September 24, 2018, 10:00:29 AM
Staggering the motors would not create any problems with ballast or list as it would weigh the same and the two motors could be set equal distance from the centre line.


Why would you need an extended U/J? Just use two propshafts of different lengths.
If the two shafts are already there, replacing one might be a problem.  A double UJ (better than a single anyway) with an extended center lets both motors sit at the same height, assuming that it has not been possible to mount the shats horizontal.
Title: Re: Motors in a 1/128th Hardy
Post by: Tug Fanatic on September 24, 2018, 10:03:50 AM
If the two shafts are already there, replacing one might be a problem.  A double UJ (better than a single anyway) with an extended center lets both motors sit at the same height, assuming that it has not been possible to mount the shats horizontal.



If the two shafts are already there and fixed in place then the spacing of the motors become fixed and the staggering idea won't help as neither motor would line up with their propshaft. I guessed that they were not fixed but ?????
Title: Re: Motors in a 1/128th Hardy
Post by: BrianB6 on September 24, 2018, 10:15:05 AM
What about going brushless?
Title: Re: Motors in a 1/128th Hardy
Post by: Tug Fanatic on September 24, 2018, 10:32:23 AM
What about going brushless?



What brushless? Significantly less that 28mm diameter with a suitably low kv?
Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on September 24, 2018, 10:59:48 AM
I can change the length of the prop shaft, It's only the prop tubes that are
fixed in now.




Colin.
Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on September 24, 2018, 11:01:01 AM
I did look at brushless motors, But found them to be significantly larger
than brushed motors.




Colin.
Title: Re: Motors in a 1/128th Hardy
Post by: Tug Fanatic on September 24, 2018, 11:09:05 AM
I can change the length of the prop shaft, It's only the prop tubes that are
fixed in now.

Colin.


That gives you a problem as staggering the motors brings them closer to the centre line and thus the two propshafts closer together for proper alignment but yours are already set.

Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on September 24, 2018, 11:12:35 AM
I could just about squeeze a pair of 400 size motors side by side, But it's very tight
so idealy something smaller in case diameter.




Colin.
Title: Re: Motors in a 1/128th Hardy
Post by: Tug Fanatic on September 24, 2018, 11:15:52 AM
I could just about squeeze a pair of 400 size motors side by side, But it's very tight
so idealy something smaller in case diameter.

Colin.



Have you considered silicon sealant as a motor mount which would cope with the tight location?
Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on September 24, 2018, 11:33:20 AM
I hadn't actually would it hold okay? And if there is a problem with the motor
is it easy to remove also. Sorry if this all sounds a bit silly.






C
Title: Re: Motors in a 1/128th Hardy
Post by: Tug Fanatic on September 24, 2018, 12:35:22 PM
I hadn't actually would it hold okay? And if there is a problem with the motor
is it easy to remove also. Sorry if this all sounds a bit silly.

C



Let me say that I have not tried this but it apparently does work  - have you ever tried to unstick cured silicon sealant?:
http://www.modelboatmayhem.co.uk/forum/index.php/topic,47847.msg484637.html#msg484637


Make sure the motor & hull are both oil free & that you don't get any silicon into the motor nor block ventilation holes. Obviously the more contact points the better & something mechanical to hold the motors down onto the silicon would be nice. A shaped bar with a short length of good quality double sided tape? (the type that holds your car number plated onto you car?)


Search here & particularly RC Groups where you will find lots of examples.



Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on September 24, 2018, 12:38:14 PM
Thanks mate I'll have a read through it. And luckily I have some of the strong
number plate tape.






C
Title: Re: Motors in a 1/128th Hardy
Post by: Tug Fanatic on September 24, 2018, 01:27:57 PM
Thanks mate I'll have a read through it. And luckily I have some of the strong
number plate tape.
C




Pleasure. You have some ideas to consider at least.


Remember with anything like this you have one go at getting the alignment correct.
Title: Re: Motors in a 1/128th Hardy
Post by: Onetenor on November 05, 2018, 09:57:52 PM
Another way to mount motors is to use TERRY TOOL CLIPS  They can be fixed back to back on a central ply plate mounted vertically so the motors are only separated by the thickness of the ply. The clips come in various diameters And two to a motor will  hold them firmly but they will be easily removable if needed. I don't know what happened to this link but hopefully the mods can fix it. If not Google  Terry Tool Clips
https://www.google.co.uk/search?q=terry+tool+clips&oq=Terry+tool&aqs=chrome.1.69i57j0l5.14582j0j7&sourceid=chrome&ie=UTF-8 (https://www.google.co.uk/search?q=terry+tool+clips&oq=Terry+tool&aqs=chrome.1.69i57j0l5.14582j0j7&sourceid=chrome&ie=UTF-8)       Here is the site for them. I think they are ideal for space saving mountings https://www.google.co.uk/search?q=terry+tool+clips&oq=Terry+tool&aqs=chrome.1.69i57j0l5.14582j0j7&sourceid=chrome&ie=UTF-8
Title: Re: Motors in a 1/128th Hardy
Post by: Onetenor on November 06, 2018, 12:06:38 AM
Testing. Looks OK
Title: Re: Motors in a 1/128th Hardy
Post by: cwmitch on November 06, 2018, 06:17:02 AM
Thank you mate I'll have a look.




Colin.
Title: Re: Motors in a 1/128th Hardy
Post by: Onetenor on November 07, 2018, 04:44:56 PM
Two motors back to back with Terry's Tool clips on a central ply plate. Screw to ply before installation or Epoxy after install==https://www.google.co.uk/search?q=terry+tool+clips&oq=Terr&aqs=chrome.0.69i59j0l2j69i57j0l2.11676j0j7&sourceid=chrome&ie=UTF-8==== Two to each Motor .Secure but easily removable if needed. A large range of sizes. To secure exactly back to back use nuts/bolts to secure.In  fact using them you can remove / install clips any time. Good luck.