Built up crankshaft machining

Shortly I will be maching a builtup crankshaft for a model single cylinder engine. The suggested method in the prints is Loctite and tapered pins or silver soldering. I want to try the Loctite method for a start. What I am looking for are sugestions regarding methods of construction that will result in a true running shaft. For example how best to clamp the parts while the tapered pin holes are drilled and reamed ie Loctite first then pin or Loctite after all driling and reaming. The shaft will be .625" how much clearance and what type of Loctite? Any and all sugestions are welcome.


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How many throws on the crank?

Make a jig. Think along the lines of a vee block with notches cut to clear the webs.

Dig around online, and see which of the locking products best suit your needs.

Look for High strength, close fit, and permanent, as the working words. Temerature resistant, too.

It used to be easy. Green was for permanent installs, and you needed a torch to get it apart. Now they have a pile of similar products, all for slightly different criteria.

Locktite, and others, make a lot of different sealers, lockers, and shaft adhesives. I cannot recall the number of the product I used for installing knobs on handles, but it did not take long to set, and has held up for a year or so of use in our shop.

Cheers Trevor Jones

Reply to
Trevor Jones

Loctite 660

what type of

Reply to
T.Alan Kraus

How does it look like? Does it have disks or just arms on the side? It is a good procedure to make both sides as one part and the split them (part off, splitting saw). If you machine it from cold drawn steel, stress relief it before machining.

Do you have a drawing? Split con-rod? There are some tricks how to get it true running with the right setup while machining. But it depends on how the crank looks like.

It doesn't help that much to Loctite and have a press-fit. A perfect chemical press-fit (AKA Loctite) needs a gap of 0.05 .. 0.1mm (read the specs!).

It's best to learn to make real press fits. :-)


Reply to
Nick Mueller

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