Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

With some encoragement from the folks here i bought a Bengs modellbau 'Karl' hit and miss engine kit, as i don't have a mill and this kit comes with all the milled parts then i hope it is going to be a good first engine to build.

Didn't take long to get here, this morning i found a heavy box in my porch :-)  So everything i had planned for today got postponed and i waded in.

Everything looks good, the base is heavy with no blow holes in the casting and all the parts are numbered and vacuum packed.  The instructions/drawings leave plenty to the imagination but that is half the fun to figure it all out.

Anyways, i couldn't resist and made a start on the crankcases.  There is quite a bit of flash on the brass parts where they have been cut so i started by dressing this off with a file.



Then using a sharpie marker for engineers blue i started marking the holes to be drilled.  At this point i realise how cruel age has been on my eyesight, but soon i had enough fairly accurate holes to bolt the two halfs together so i could file both crankcase halves to be identical...ish



Using a socket as a guide i drilled and tapped the main bearing caps, good old fasioned pillar drill and digital engineers level was a life saver here to get the holes vertical and true.



More drilling and tapping and only one M2 tap broken off in the hole with could be punched out of the brass with no lasting damage





Before my wife realised something was going on in the garage both crankcase side plates were done.



Next job was to join the two halfs, to my suprise it turned out square and level, turning out to be quite a good day!



As luck seemed to be on my side today i turned both faces of the baseplate on the lathe and drilled the mounting holes.





I guess drilling and tapping the faceplate of my lathe to mount the base for turning will make all you engineers out there cry but it got the job done :-)

Before i knew it was 7 o'clock and time to quit, but i had a really fun day doing the easy bits and at the end i have the crankcase bolted to the base and all is square :-)



Kind regards
Ade

The fact that you made the time to work on it and seeing the progress that you made on it speaks volumes for the Quality and Your Enjoyment!!!

It's looking good and I'm enjoying this thread Thanks.

Found my first major issue today, thought i would see how i got on with the cylinder jacket and liner. 

I would like to make this a water cooled hopper type engine rather than air cooled, there is some pictures online of a lovely job someone has done on one of these engines with hopper cooling and it is very inspiring, plus after the M90 i realise these things get hot if you work them.  I don't have a real plan so drifted into machining the jacket and liner.  The plans step the liner about halfway down so the liner is trapped between the cooling jacket and crankcase, i decided to reduce the length of the step but keep the same way of retaining the liner, with the jacket holding the liner in place at the rear and a 3mm lip to hold the front of the liner allowing me to hollow out the centre section of the jacket for the water cooling.

Machining the liner went well



As did the jacket



Got a perfect fit of the liner in the jacket, more by luck than good jugement 

It was then i noticed the problem, the inside of the liner is 'supposed' to be finished as supplied, but running my finger around the inside revealed a raised flat spot where the tube was welded dagnabbit!  Another mod i had planned was to use piston rings and and aluminium piston rather than the rather odd and heavy looking affair outlined in the plans, to do this i ordered a pair of the 25mm rings that Bengs offer, and this is my problem, the bore is already 25mm so i have no room to clean up the ridge in the bore.  I don't think a hone will remove the ridge before oversizing the bore, so i either have to order another liner from Bengs and hope it is better or make a liner from scratch, any advice here would be gratefully received 

This picture does not show it too well, but you can just see the weld undercut on the right



Ade

Hi,
 Please keep posting your progress! I have used DOM tubing as liner with some success, not sure that this would be any advantage than ordering part from Bengs.

Len.

http://www.speedymetals.com/information/material17.html

Thanks for the info Len
Kind regards
Ade

Interesting project and you have made a quick start .
As for drilling and tapping your face plate ?? Nothing wrong with that as I  have  seen many a face plate with tapped holes in it .

Cheers
Dennis

looks GOOD.Jin

I would like to thank you all for your kind words of encouragement 

Probably won't get much done in the week because i am still working, for my sins.

Hopefully the paint will arrive tomorrow and the reamers before the weekend, fingers crossed.

Kind regards
Ade