Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: The_Commander on June 26, 2008, 11:03:57 pm
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Ive just bought a new boat (matchbox corvette0 with a 2mm threaded graupner prop shaft, but wish to fit a better prop than the plastic graupner one, howevere the only brass ones i can find have a 4mm threaded hole, anyone got any ideas?
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Change the prop shaft to a 4mm one.
Bob
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yes but how easy would this be, tube surrounding the prop shaft seems pretty well fixed in, and bearing holes at either end arent big enough to accomodate 4mm prop shaft.
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Any idea what the shaft is fixed in with?
Epoxy, P38 etc
Bob
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I think Deans Marine do 2mm Props: http://www.deansmarine.co.uk/
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Or Prop Shop will make them.
Bob
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get in touch with astec he does 2mm shafts that have a m4 end and it would pro do what you want without changing shaft tube
http://www.astecmodels.co.uk/products-big.php?gref=scaleshaft.jpg
hs93
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Most brass ( but not all) ones do have 4mm threads these days. There are two possible options.
One is to drill out the threaded hole in the brass prop and glue, (metal epoxy), or carefully solder in a brass 2mm nut which will then screw on your existing shaft.
The alternative is to screw your plastic Graupner prop on to a long 2mm bolt and dip it into boiling water. Then use a pair of pliers to "tweak" the prop blades to give it more pitch and therefore "bite" on the water. When the prop cools down the change in shape will be retained. Obviously you will need to twist each blade to the same degree but it's easy enough - you don't need much and it will vastly improve astern power!
I have used both methods successfully.
Colin
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O0
All very sound advice but..
Why do you want to change it?
I had a brass 3 blade prop on my Huntsman and switched to a 2 blade Graupner "plastic" and found much better performance, if its black "plastic" then its a pretty sound prop.
Or on the other hand I could be having a Senior moment.
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SHG supply M2 threaded props also:
http://www.shgmodels.com
Download their catalogue and have a read through.
-Rob
ps Their details are also in the Mayhem! Traders Directory.
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The boat is a 1/72 Matchbox flower class corvette, with the plastic prop it hardly even manages to move itself!
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What motor is in it ?
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:)
A picture would be most helpful...
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My cameras not working at mo, motor is a graupner 400
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A 35mm 3 blade Rivabo prop wil produce slightly over scale speed.
If you dont want to change propshaft Prop Shop can produce a prop this size on a 2mm thread.
My preference would be to remove the shaft and fit a 4mm one, but this prop will be fine for performance.
Bob
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I don't know if you have any facilities to make parts but this is how the end of the astec shaft is done. its just a threaded section fitted on the end of a shaft to take the m4/4ba props its a simple fix.
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sadly i have no access to suitable equipment to make one of these,grrrr
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:)
SHG have these props on their site, all at M2:-
Graupner Miniature Racing Props
2318.26 26mm Dia 36mm Pitch LH M2 £2.50
2318.26L 26mm Dia 36mm Pitch RH M2 £3.50
2318.29 29mm Dia 35mm Pitch LH M4 £2.50
2314.30 30mm Dia 36mm Pitch LH M4 £2.50
I'm sure one of these will move you along a bit!! and @ £2.50 they got to be worth a go?
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S.H.G. MODEL SUPPLIES
http://www.shgmodels.com/acatalog/
Raboesch Brass Marine Propellers
20mm to 40mm Props can be supplied bushed to M2 for use on miniature shafts and models.
Page 48 0f the downloadable Catalogue
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As was pointed out in post number nine gentlemen.
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Problem hopefully sorted, ordered a 2mm prop shaft with a 4mm threaded end and a new prop! 7.2 volt battery pack ive got seems bit strong for my graupner 400 motor though, ah well!
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Don't know if this will help.
http://www.modelboatmayhem.co.uk/forum/index.php?topic=5226.0
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I have had a few diferent props on my corvette in the past seven years, and a few different motors. The choice of prop made no noticeable difference, but the choice of motor and adjustment of the shaft end play did. The ideal was a 385 or equivalent running on half its rated voltage, direct driving a 35mm three bladed prop. Brass or plastic made no difference except to appearance.
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Prop it did have was a tiny plastic one that has seen better days, anyway brass looks better. As for my shaft its got a nasty kink in it somewhere so needed replacing anyway.
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You think you've got problems removing the props.....
(http://farm3.static.flickr.com/2256/2248727373_e169e204df_b.jpg)
http://www.flickr.com/photos/mastermariner/sets/72157603869441876/ (http://www.flickr.com/photos/mastermariner/sets/72157603869441876/)