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Hello Joe - thanks for your interest - it's always nice to hear that someone is following along. It will be a while before the launch but hopefully if things work out right it should be this summer.George, my thanks as always for your continued interest. Re the con-rods when I read your post I wasn't sure what you were referring to at first. A quick look at the pic soon put my mind straight however At first I hoped it might be an optical illusion but then a quick visit to the workshop put things in perspective I realised then that when I selected the material I had the dimension of 8mm in my head - that of the diameter of the boss and not the width across the them Agh! we've all been there I've taken a good look at it and think I will press on with what I have - the material is just over 10mm wide - as I think, if necessary, I should be able to solder some pads on the outside to increase the width. I could also decrease the width of the slot slightly as I can make new cross heads to fit. Call them the new slim line D10 rods With regards to the pump drive my intention is to make a wheel and worm. I have never done it before but intend trying to make the wheel using a 3/8 whit tap as a hob - this will very much be a 'suck it and see op' first and if successful will make the worm to match - is the HPC worm single or multiple start? as I have been thinking that it may run too slow on a single start. The intention is for the worm to be held on the shaft with a 4 ba caphead bolt. If this doesn't work out as well as hoped I will re-machine the shaft to take an insert on which to mount an HPC worm as you have done. Just in case do you have the HPC part no's required?I still have the pics of your pump set up so will copy them in the most part, if not all.Thanks again - I don't know how much further I would have gone before the penny dropped but at least I'm setting off now with the mistake firmly in mind Hope this finds you well and improvingKind regards - Ramon
Hmmm....I think if it's a multi start worm, the lead is greater than a single start worm.....so a double start with twice the lead would be half the ratio.....What am I missing here?Dave
Quote from: steamer on April 16, 2016, 01:20:29 PMHmmm....I think if it's a multi start worm, the lead is greater than a single start worm.....so a double start with twice the lead would be half the ratio.....What am I missing here?DaveDave ,According to H.P.C. gear manufacturer and I quote, ( The ratio is No of teeth on the wheel divided by the No of teeth on the worm )Think of a 10 tooth spur wheel and a 20 tooth wheel. 2:1 ratioGeorge.
Bob,Yes you could drive the pump from a main shaft eccentric but it would pump too much water into the boiler.I can only say that by experience with D10"s and Scotch marine type boilers, my current boiler is 4.75" dia x 5" between end plates, a 1/4" dia pump x max 3/4 " stroke running at 120 strokes /min is enough to keep my boilers up all day as long as I have enough gas and water, I use pond water and that is why I have found that a reduction of between 4/1 and 6/1 is about right. I also make a disc on the cross shaft that has various pitched holes that allows you to increase or reduce the stroke as required.If you came direct from the main shaft which depending on boat size and prop the main shaft on the D10 will turn between 500- 700 r.p.m. so that would produce too much water for the boiler so then you have to start thinking about boiler level control and feed water bypass valves either manual or electronic.I should have read Daves post closer as his quote ( so a double start with twice the lead would be half the ratio ) which is correct, it was the ( What am I missing here ? ) quote that Foxed me.At College 60 years ago as a first year student it was drummed into us that " The number of teeth on the follower divided by the number of teeth on the driver " gave you ratio it's the same with worm gears. Thanks for your inputGeorge.