Quantcast

John Builds Kerzel Hit & Miss

Help Support HMEM:

simister

John
Joined
Jul 19, 2014
Messages
188
Reaction score
33
Location
Melbourne, Australia
HI Guys.

Well after all these months after building the Webster, I have finally made a start on the Kerzell Hit & Miss. I have finished the base, which seems to have gone well. Next is the complicated cylinder body.

Brian, I have been following your post on this engine and following the changes in dimensions that you have made. Is there any other variation other than your posts that I should be aware of.

John

IMG_20160122_150357630.jpg


IMG_20160123_110540715.jpg


IMG_20160123_123204823.jpg


IMG_20160124_123620286.jpg


IMG_20160124_140525896.jpg
 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,404
Reaction score
4,978
Location
Barrie, Ontario, Canada
Simister--It`s been a long time since I built the Kerzel. I have it here on a shelf, but I don't really remember what changes I made. If I can help with anything specific I will.--One word of advice though----on all of my hit and miss engines, I used a Viton ring on the piston.-It is quicker and easier, and my cast iron ring making skills really suck!!--But---I never got any of my hit and miss engines to work as good as the other builds I have seen posted. They work, but there is so much drag from the Viton ring that the engine would never coast as long between "hits" as they should have. I never realized how much drag there was, because I never had a good running engine with a cast iron ring to compare it to. After building my most recent two cycle engine with the piston lapped into the cylinder, I was absolutely amazed at how little "drag' there was compared to my engines with Viton rings. I am certain that pistons with a cast iron ring would also have a much lower drag co-efficient. So---I recommend that you use a cast iron ring or lap the piston into the cylinder and don't use any ring.---Brian
 
Last edited:

simister

John
Joined
Jul 19, 2014
Messages
188
Reaction score
33
Location
Melbourne, Australia
Well, it has been a few years since I started the Kerzel Hit and Miss. However, now that we are in lockdown due to the virus it is a good time to get back into this project. I have started on the Base Sides. I turned the curved profile by tapping a 8 mm thread in a plate which held the blank. I was then able to put it in the 3 draw chuck. This seemed to work well. I had tried doing it in the 4 draw chuck but was not happy with the result. Also, there was very little material for the jaws to lock on to. Next is the angle cut. I think I will use Brian's method and scribe a line on the face and mill to the line. John
20200723_112457.jpg
20200723_112445.jpg
20200723_114338.jpg
 

simister

John
Joined
Jul 19, 2014
Messages
188
Reaction score
33
Location
Melbourne, Australia
Brian, I have seen a lot of your posts on lapping the piston to the bore. What success did you have with it and what method proved the most successful? I have been looking at buying an Acro Lapping tool for the job. However, I am still looking for as much advice as I can get before I go ahead with Acro.

Any help on this would be great.

John
 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,404
Reaction score
4,978
Location
Barrie, Ontario, Canada
Having tried many different ways, I finally bought a set of brass laps and use them with 600 grit aluminum oxide paste. Something that works extremely well but is rather dangerous, is to bore the cylinder to nominal size, then use a 3 stone brake hone to take out most of the machining marks. When making the piston, turn it very carefully to a point where it will just begin to enter the cylinder, but will not slide fully into place. Then put the cylinder into the 3 jaw chuck and have it turning slowly. Coat the piston with diamond paste or 600 grit aluminum oxide. Make a temporary "handle" for the piston, and work it slowly in and out of the bore, going a little deeper each time. This way the piston becomes the lap. THIS IS EXTREMELY DANGEROUS!! You have to be prepared to immediately let go of the piston if it "grabs". It will wrap you up in the lathe in micro-seconds. Sometimes it grabs so tightly that I have to take the cylinder and piston together out to my arbor press and using a piece of wooden broom handle for my "presser" separate the piston and cylinder. If you do this correctly, you won't even need any rings.--- or---You can put the piston into the lathe chuck and hold onto the cylinder with your hands. If you plan on using Viton rings or cast iron rings, then you can lightly hone and lap the cylinder with an Acro lap and turn the piston to .002" undersize. The rings will expand to take out any possible compression leakage.
 

simister

John
Joined
Jul 19, 2014
Messages
188
Reaction score
33
Location
Melbourne, Australia
Thanks Brian for sharing that. OK, did you use the brass laps at all or only used the piston to lap the bore? I am happy to purchase an Acro Lap if you think that may be a better option.

I understand that you used Viton rings (I used these in the Webster) in the Kerzel and was not entirely happy with them. Has the running of the Kerzel engine improved over the years with the Viton rings or would you still prefer to lap the piston to the bore? John
 

BaronJ

Grumpy Old Git.
Joined
Dec 6, 2013
Messages
1,095
Reaction score
495
Location
York, North Yorkshire
Hi Guys,

A method I've used to lap and polish bores, is to use a piece of wood dowel with a slit in the end and fine emery cloth. Put the work in the chuck and the dowel in the tool post. This way you have full control over both the work and the depth of the lapping.

I've even turned a wood plug and done the same with emery paste on occasion.
 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,404
Reaction score
4,978
Location
Barrie, Ontario, Canada
No, the Kerzel has not improved over the years. There is simply too much drag from the Viton ring. Either make it using the dangerous method I outlined and use no ring at all, or use the Acro lap and 600 grit aluminum oxide paste to smooth out the bore. Then turn the piston for a "sliding fit" into the bore. The piston will be about .002" less than the bore diameter.
 

Misterg

Member
Joined
Apr 20, 2020
Messages
11
Reaction score
3
Location
UK
I understand that you used Viton rings (I used these in the Webster) in the Kerzel and was not entirely happy with them.
I don't know if you've read this thread:


It seems Brian advocates a tighter fit for the O ring than some other responses on that thread (0.058" deep groove for a 0.070" section ring = 0.010" / side compression after allowing 0.002" piston-cylinder clearance vs 0.005" / side or even 0.005" total from others). It would be interesting to see if the Kerzel was happier with the lighter contact between ring and cylinder - I hope so, as I'm building a similar engine and have used the 0.005" total compression for the O ring.

It is interesting (to me at least!) that the Farm Boy design has no compression between the O ring and the cylinder at all (it has a 0.110 deep groove for a 0.094 section O ring) yet still seems to run well.
 

simister

John
Joined
Jul 19, 2014
Messages
188
Reaction score
33
Location
Melbourne, Australia
Thanks Brian, I will order a .750 Acro lap from the US and use the method you suggested of lapping the bore and machining the piston to fit. I was also going to make the cylinder and piston in cast.

If I turn the piston to the bore, do I still need to put some grooves in the piston for oil lubrication or leave the piston as is?
 

doc1955

Gone
Joined
Aug 26, 2009
Messages
1,168
Reaction score
103
I'd say the best thing is to make the cast iron rings as per plans. But then again I don't like using -O- rings and find that cast iron rings are pretty simple to make. I just finished 2 Kerzels that I posted a build to on my youtube channel. They both run very well and I can hand start them now after running a few times. Anyway thay is my 2 cents worth just make the rings.

 

simister

John
Joined
Jul 19, 2014
Messages
188
Reaction score
33
Location
Melbourne, Australia
I'd say the best thing is to make the cast iron rings as per plans. But then again I don't like using -O- rings and find that cast iron rings are pretty simple to make. I just finished 2 Kerzels that I posted a build to on my youtube channel. They both run very well and I can hand start them now after running a few times. Anyway thay is my 2 cents worth just make the rings.

Thanks for your input, I will have a look at your video on ring making. At this stage I will go for lapping the piston to the cylinder. However, I thought that when I machine the Piston I would cut some rings and have a try anyway. I have a lot to learn in model engineering and trying to keep it simple whilst I gain experience. John
 

simister

John
Joined
Jul 19, 2014
Messages
188
Reaction score
33
Location
Melbourne, Australia
Finished making the bearing caps today. I should of finished them earlier in the week, however, I got to the last part of the operation and cut on the wrong side. Frustrating as I had nearly finished them. It was a good lesson as I had been in the shop all day and was getting tired. I should of left it until the next day. 20200731_110543.jpg
 

simister

John
Joined
Jul 19, 2014
Messages
188
Reaction score
33
Location
Melbourne, Australia
I am about to start the crankshaft. I notice that some people have made it as per the plans from 1 piece and others made it from multiple pieces. I notice that Brian made it from 1 piece and also made it up from steel rod. Any suggestions on the best method for this part?

John
 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,404
Reaction score
4,978
Location
Barrie, Ontario, Canada
Either way will work fine. One piece crankshafts are scary, because you have to offset them so far to turn the con-rod journal, and that means machining with a rather amazing amount of "stick out" on your turning tool.
 

minh-thanh

Well-Known Member
Joined
Dec 29, 2016
Messages
670
Reaction score
333
Location
Viet Nam
I made crankshaft for my first engine from multiple pieces ( and a few more after that ), made of brass, and it had been running for many hours and still not broken.
if you make a steel crankshaft from multiple pieces, it will be very difficult to damage
 

simister

John
Joined
Jul 19, 2014
Messages
188
Reaction score
33
Location
Melbourne, Australia
Brian, I am leaning towards multiple pieces as it concerns me of getting accuracy from one piece. How did you avoid distortion when you silver soldered the rods? John
 

Latest posts

Top