BUILDING A TIGER TANK

Part 5 by Vince Cutajar

Cleaned up the sprockets. Used the same method as for the idler. Had to use the 4-jaw chuck as the 3-jaw was too small.

Used the 4-jaw chuck to also create a light chamfer on the sprocket ring teeth.
Next a trial assembly of the two types of road wheels.
Then my introduction to Milliput.  I thought I would do something easy first. So I filled some straight gaps on the inside of the lower hull.
For my first attempt at making simulated weld seams, I wanted do it somewhere where it is not very visible just in case I muck it up. So bottoms up! Turned the hull upside down and did my first attempt on the floor of the hull. Used a gadget I saw when I ordered the Milliput from Amazon and although I wasn't sure how it will work out, I am happy to say that it gave me a nice Milliput sausage without any effort.
Finished off the weld seams on the hull floor. I felt more confident about it. That "sausage extruder" was less than a fiver and is worth every penny.

when I did the trial assembly of both types of road wheels, I had a minor problem when screwing the inner cap to one of the hub caps. So decided to  clean and check all hub caps and inner caps.

When threading one aluminium component into another I am always careful as there is a good chance of galling and once the parts jam you’ve basically had it. So first I inspected both female and male threads for machining debris. Most of the debris was noticed to be on the male thread. I cleaned these up with a wooden tooth pick. One could also use a blast of compressed air (using safety googles!). I only had a problem with three or four parts. Most of the time the problem was on the female thread. So I back it off and try hand tightening again until I feel the obstruction, then using an 8mm spanner carefully try to go beyond the obstruction which most of the time solves the problem. When I felt that gently using the spanner this was not going to help, an inspection of the threads with a magnifying glass always finds the problem which in my case was solved by using the metal point of a smaller divider to either remove a burr or fix a slightly deformed thread.

Removed the machining marks on the hub covers and did an experiment with one of the road wheels. Looking at a photo of a steel road wheel I noticed that the nuts used over the locking tabs look slightly larger than the nuts used on the hub. At first I thought of using one size smaller hardware on the hubs but I think then they will look too small (plus being a costly exercise). So then I thought, how about increasing the size of the hardware which has the locking tabs from 2.5mm to 3mm?
I drew in CAD the hub cap cover so that I could draw the position of the two small bolts.
At first I was going to machine a template from the drawing so that I could drill the holes but then I remembered that I can actually find out the X and Y co-ordinates of the location of the bolts from the CAD drawing. And that's what I did. Having a DRO on the milling machine made life easy to locate the positions on the actual cover. At first I was going to just drill holes with the intention of later on gluing the bolts in the holes but at the last moment drilled and tapped for the bolts.


Part 4 here   Part 6 here

 
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