loctite used on crankshaft

[John RutzenParticipant @johnrutzen76569]

Hi, I am making the crankshaft for my 31/2 gauge Lion. The central portion is fully taken up by the 4 eccentrics. I am using Loctite and pins to hold it together. What I am wondering is how to ensure that the stuff doesn't get into the eccentrics and stick them to the shaft ? Do you think grease would be effective?

[John RutzenParticipant @johnrutzen76569]

[old martParticipant @oldmart]

Yes, if you use a very thick type which won't get where the Loctite goes. When the Loctite has had time to cure, you can wash the grease out with solvents if you want. We used to use this exact procedure to fit and pretension the studs which held propeller hubs onto the gearbox output shafts of C130J Hercules and other turboprops. We used to use a thick silicone grease thinned down with a solvent like trichloroethane, and brushed on carefully with a small artists brush and allowed to thicken up before assembling.

Edited By old mart on 01/09/2019 18:09:09

[John RutzenParticipant @johnrutzen76569]

Thanks, yes the loctite is 638 which is very thick also so it won't run everywhere. I'll put grease on the shaft and inside the eccentric and only put loctite in the hole in the web so none will get pushed into the gap or do you think I can safely put it on the shaft as well?

[old martParticipant @oldmart]

Sorry, I'm not familiar with steam engines, you will have to decide where the grease goes, any parts which are bearings need a little as long as you avoid contaminating the joints to be bonded. I use 638 normally, but had to use 620 recently, as I was not sure of completing the assembly fast enough before the 638 cured. The 620 is just as strong, but takes much longer to cure. A little Loctite on the shaft is unlikely to displace any grease as the joint is assembled.

Edited By old mart on 01/09/2019 20:02:22

[John RutzenParticipant @johnrutzen76569]

Thanks for the help. I'll be doing the job this week so I'll post as to how I got on.

[Malcolm HarveyParticipant @malcolmharvey97633]

Thanks for posting this question and the replies. I am also building a 3½" gauge Lion and I have decided to use the same method of construction for the crankaxle. The puzzle was how to keep Loctite out of the eccentrics and stop collars. Now I have the answer . I have now had 3 attempts at building the crankaxle by LBSC's method and every one has ended up bent!

[duncan webster 1Participant @duncanwebster1]

A brave soul (braver than me perhaps) would loctite the whole thing together, eccentrics and all. It should be possible to set the eccentrics relative to the cranks (perhaps with a pin parallel to the axle to stop it shifting whilst you're setting the other half). I think Don Ashton describes how to pin 2 eccentrics together for Stephenson's, same principle it's only a little step to pin them to the crank web.

You can get slow setting loctite, and if it were all pinned up you could do it step by step, so not a great rush.

 

Edited By duncan webster on 22/09/2019 23:52:25

[John RutzenParticipant @johnrutzen76569]

Hi, I've successfully made my crankshaft using the methods suggested. I used a smear of copper grease on the eccentrics in case any loctite got in the wrong place. I did not have any problems with it. It runs perfectly true. I set the crankshaft between the 3 jaw chuck and the tailstock chuck for the final joint..I did the webs first, putting a bar through the other two holes, then one end of the centre portion.,put the eccentrics on [ drill the grubscrew holes first! I drilled the pin holes 3/32 through the webs before I put the thing together. Drilling such a long hole can end up with a broken drill. I finally loctited the pins in. I find the 3 1/2 drawings frustrating, Some of the dimensions aren't right and things don't fit. It's the first 3/1/2 gauge I've made and it's harder to make than a 5 inch gauge for sure. I'm presently trying to make the slide bars.

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