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Old 11-10-2016, 03:51 PM   #21
apointofview
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Kvom thanks I am going to try the locktite this time, but to show my ignorance how do you use guage blocks to keep it all aligned. I guess i just cant picture it in my head. This time so far i mounted the new slightly oversize brass disks on their respective shaft stubs and then mounted the shaft in the lathe and finished off the final dimensions so those parts spin true. Getting the crank throw correct seems tougher.

fcheslop thanks for that link those are really nice renderings and it helped a lot, it cleared a few questions up I had. I will get them printed out.

Pete


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Old 11-10-2016, 08:59 PM   #22
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Pete,

Julius, who does those plans always does a great job of them and in fact, you are better off not printing them out as if you are using the correct PDF reader, you can select very large views of every component. If you printed each part out, you would end up with about 100 pages.
He puts lots of plans on here, and this is one of his latest, for the beginners amongst us.

http://modelengineeringwebsite.com/Oscillator.html

John


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Old 11-10-2016, 10:47 PM   #23
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Use of gauge blocks works like this. Assume that the disks are flat on both sides. Then I place block(s) equal to the desired separation between them so that they are forced to be parallel and the correct distance apart while the loctite sets. I use Loctite 620.
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Old 11-11-2016, 12:41 AM   #24
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Pete.

Make your discs the exact same dia and drill thro' the centre to suit your shaft ensuring that they are machined parallel.
Make a small piece of your shaft material as a sliding fitting set it up vertical in your bench drill and feed the 2- disc blanks on to it, wind out the "X" or "Y" table to the radius of the stroke ensuring that the discs are held firm and square to the vertical, drill thro' to suit the journal dia.
Make another piece of round material to suit the big end journal and slip it thro' the journal hole, you now have the journal parallel to the main shaft.

I use Loctite 603 now think of doing one side at a time by putting some Loctite on the main shaft and slip a disc onto it's position, leave for 30 mins and then put the big end journal in with Loctite and leave for 30 mins, you can then slide the other disc into position with Loctite and a smear of Loctite on the journal and press both into position.

Leave the assembly over night to cure and then drill a 1/16" di hole in each of the discs, thro' the journal and main shaft with the ends sticking out both sides, use a piece of mild steel rod or a piece of brass rod making sure that you have the Loctite going right thro' before pushing the rod thro', leave overnight to cure , flush of the ends , cut out the central piece of the main shaft and.

Do a few practise runs before glueing up as the Loctite goes off quite fast.

Here are 2- pics of a Launch engine shaft with 4- discs with the journal holes and main shaft holes drilled and kept in position before assembly.

I hope this will help you.

George.
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Main shaft:2.jpg   Milling crank web:2.jpg  
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Old 11-12-2016, 12:32 AM   #25
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Thanks guys I can see what I need to do now, those replays are a lot of help. It seemed simple just to look at the drawings but looks were deceiving!

I do have another question, the disks are just round, most of the time crankshafts are cut to counter weight the piston and connecting rod. Should I remove some material from the crank pin side of the disks or does this design run fine as is ?
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Old 11-12-2016, 11:47 AM   #26
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Quote:
Originally Posted by apointofview View Post
Thanks guys I can see what I need to do now, those replays are a lot of help. It seemed simple just to look at the drawings but looks were deceiving!

I do have another question, the disks are just round, most of the time crankshafts are cut to counter weight the piston and connecting rod. Should I remove some material from the crank pin side of the disks or does this design run fine as is ?
Pete ,
It makes no difference to the engine performance, stick with the designers discs.

I have in the past made the crank webs with the balanced cut outs and some with just strips of mild steel and I find no difference to performance.
At this size it's purely aesthetic.

George.
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Old 11-14-2016, 04:58 PM   #27
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Ok thanks George that's less work !!

So for my next attempt I carved up two more webs to replace the ones I destroyed and then drilled them up for set screws to pinch the shafts. I shy away from permanent attachments because it seems everything I own needs fixing at some point. I positioned the set screws for the throw in such a way to allow for carving the web for balancing, that was before George let me know there is no need to do it. I am going to set it all with locktite 242 the blue removable stuff. If that doesn't hold up then pinning and serious locktite will be in order. At least this time everything is nice and straight if I have to lock it all down forever. Next up is the cam.

Pete

ImageUploadedByModel Engines1479142437.413736.jpg

ImageUploadedByModel Engines1479142461.496118.jpg

ImageUploadedByModel Engines1479142488.632444.jpg

ImageUploadedByModel Engines1479142501.148703.jpg

A bit of video just to see it spin

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Old 11-14-2016, 11:16 PM   #28
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Pete,
Nice runner, you shouldn't have any trouble with the socket grubs it's a well supported shaft, if you do don't use the 243 Loctite it's only for thread lock.
If you have to, be brave and use Loctite 603 or 620. and it will never move.

Keep up the good work.

George
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Old 11-16-2016, 01:49 PM   #29
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Time for the valve cam. I didn't get as many pictures for this one but here's what I got.
ImageUploadedByModel Engines1479303234.743094.jpg
The brass was rough cut to size and then I drilled the offset hole. I mounted it on a hunk of drill rod and tried to put it in my 4 jaw chuck to get to the final dimensions. Problem was the jaws wouldn't close on the rod in the offset position it needed. I ended up having to put a second piece of rod in the jaws to allow them to be tightened to the 1.3mm offset called for.
ImageUploadedByModel Engines1479303797.213776.jpg
This is the retaining ring

ImageUploadedByModel Engines1479303846.646785.jpg
The securing of the ring is supposed to be a couple of tiny countersunk screws that I don't have. I ended up modifying the cap screws to lower the profile to flush out on the thin ring.
ImageUploadedByModel Engines1479304018.246928.jpg

ImageUploadedByModel Engines1479304033.081364.jpg
This is where it will live. Timing it will come later

Looks like cylinder parts are next

Pete
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File Type: jpg ImageUploadedByModel Engines1479303754.162402.jpg (48.7 KB, 438 views)
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Old 11-19-2016, 01:30 AM   #30
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Default A Smaller Steam Engine For A Smaller Boat

Cylinder end covers are next. They seem simple enough and here is what I got done
ImageUploadedByModel Engines1479518312.354772.jpg
ImageUploadedByModel Engines1479518341.092385.jpg
ImageUploadedByModel Engines1479518369.342305.jpg
ImageUploadedByModel Engines1479518386.495327.jpg
ImageUploadedByModel Engines1479518402.344511.jpg

So the two of the covers need work on the back side of them for o-rings and two have a raised area for clearing the nut inside the cylinder, and all of them need a bit of thinning down.. I left them a little thicker because I can't part off pieces right at perfect dimensions with nice finishes. So here is where I need help from you guys...

How do I shave down the back of these tiny disks?

I can hold them to drill the three holes 120degrees apart and get the o-ring grove cut in the three jaw chuck but the chuck is in the way for thinning down the part
ImageUploadedByModel Engines1479518988.998934.jpg
ImageUploadedByModel Engines1479519004.185961.jpg


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