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Changing mount bolt holes to suit a different prop boss

Bob Moore

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You may have seen my long and tortuous thread about trying to get a Solo 210 I acquired to run properly, or more accurately restart after it had been run. (It had sat in someone's garage for 20 years)  After wasting £200 on it I finally gave up.  Bought an Adventure F3 that needed a starter motor and my old one fitted, had a few other little things to sort, engine mounts, fuel lines etc. but that paramotor starts, restarts and runs well. 48 inch prop.


I also acquired another motor, a more recent Solo 210 unit with CDI ignition for free and have transplanted it into my original machine which had a 4 bladed 36 inch prop, lighter weight, smaller cage .  Lo and behold I started it today, hand start, but only briefly as it has no prop on it at the moment.  So here's the issue.  The old motor has a mount with 6 screws for the 4 blade 36 inch prop. The motor I acquired for free has a boss with 4 bolts. It's looks like a hard job to switch the bosses (I'd need to switch both) so I hope to drill out 4 holes  in the wooden boss to fit the new boss.  I realise this is a risky procedure balance wise.  Don't want to shell out lots of bucks as this motor hadn't been run for 8 years and as it was I spent £200+ trying to get the original working.


Does anyone know a safe and reliable way to re-drill a prop for a different mount please.  I just looked at some prop specialist web sites and it would cost more than this thing is worth to get them to do it.

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Get a bar that fit's tightly through the middle of both props (6 hole on the bottom) and then turn the top one (the 4 hole one) until you can see some meat to drill into. 

This is not something I have done, but have seen done. ( I think a couple of them get quite close in terms of holes so be careful ) 



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Thanks Simon, I have provisionally marked it out and it is close to some holes, but that said it's clamped by a big plate on the outside and I'm confident it won't weaken the hub.  I  was given some other 45 inch props that have been re-drilled though haven't tested them to see how successful it was. (Too big for this cage though.) Most important I feel is to find a workshop with a good solid bench drill so that as well as being properly positioned that they are vertical! I can see a potential for all kinds of problems if they are even just a degree or two off! 

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