Author Topic: Vertical hit and miss engine  (Read 25639 times)

Offline Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #45 on: June 27, 2019, 02:39:12 PM »
The port holes which get drilled into the head will not be done until after the valve cages have been made and installed into the head. Then the cylinder head and the hole in the side of the valve cage are both drilled at the same time.

Offline Johnmcc69

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Re: Vertical hit and miss engine
« Reply #46 on: June 27, 2019, 08:48:56 PM »
 :popcorn:
Looking good Brian!
 Reminds me of a Briggs & Stratton, just need the cooling fins on the flywheel on the magneto side.

 John

Offline Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #47 on: June 27, 2019, 09:14:51 PM »
I have a stick of 7/8" bronze that I bought a while ago. I don't know exactly what composition of bronze it is, but it's nasty stuff to machine. However, it did work quite well for an oil filler cap. You can't see it, but on the 3/8"-16 threaded shank there is a cavity .030" deep for a 1/16" cross section o-ring to prevent oil from leaking out. Also, my $20 mitre gears came today, and they look quite good. The bore on the smaller gear looks a bit too small to me, so I may open it out to 5/16" diameter.

Offline Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #48 on: June 27, 2019, 09:17:19 PM »
Johnmcc69--Those fins on the flywheel go in very well if you have cnc capability. However, since my machines are manual, it would probably add a year to the project if I had to put fins on it.

Offline Johnmcc69

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Re: Vertical hit and miss engine
« Reply #49 on: June 27, 2019, 09:40:03 PM »
Johnmcc69--Those fins on the flywheel go in very well if you have cnc capability. However, since my machines are manual, it would probably add a year to the project if I had to put fins on it.

 Maybe a clever bit of fixturing & a separate index plate mounted to the rotary table & you could pull it off...
 :stickpoke:

Offline Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #50 on: June 28, 2019, 04:16:05 PM »
Whenever I buy bevel or mitre gears, they are never supplied with the dimensional data on how to set them up for a proper mesh. I can figure it out using the center finder and read-outs on my milling machine, but I always have to make a test block and put the holes for stub shafts in the right position to really confirm my numbers.

Offline Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #51 on: June 29, 2019, 01:13:38 AM »
Sometimes ya just don't know--how big things are going to be until you have them "in hand". My bevel gears came yesterday from somewhere in China. They look great, they are well made---but--They look too big to really please me. They are big enough that I think they overshadow the engine. Of course this doesn't show up until you have modelled them and put them into the overall assembly. Now I have to decide whether I go ahead and use them, (they are 20 and 40 teeth) or reorder the next smaller set which are 15 and 30 teeth. I still have to make valve cages, valves, piston, con rod, a crankshaft, and a carburetor. And I'm scheduled for cataract surgery on 15th of July and again on the 29th of July. The gears are not expensive at only around $20 for the set. This shows the current gears that came yesterday. I have decided while typing this that I will go ahead and order the smaller gear set. Time is not supposed to be critical on this engine, and I think it may look better with a smaller gear set.

Offline Ye-Ole Steam Dude

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Re: Vertical hit and miss engine
« Reply #52 on: June 29, 2019, 01:34:38 AM »
Hello Brian,

I love all your great designs and work, so I will add my two-cents in here from a positive view. From your 3D drawing the gears do look a bit disproportional, but they really do not look that bad. However the smaller set most likely will scale to your engine more closely.

Have a great day,
Thomas
Thomas

Offline Johnmcc69

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Re: Vertical hit and miss engine
« Reply #53 on: June 29, 2019, 01:54:35 AM »
Maybe a fabbed shroud around it & the old rope starter..

 John

 Great design work Brian!

Offline Jasonb

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Re: Vertical hit and miss engine
« Reply #54 on: June 29, 2019, 07:08:26 AM »
Of course this doesn't show up until you have modelled them and put them into the overall assembly.


I'm surprised at that Brian. Most gears will not only give the tooth count but the tooth size and in the case of most Chinese gears that is going to be a module gear rather than DP so yours would likely have been sold as 1.0MOD, 1.5MOD etc. Easy enough to look up the size of gears like this and even find a parts library to download a file from so you can model them at least the basic diameter as the boss can vary a bit.

You probably only want 0.5MOD on that size engine, most of te cheap far eastern ones on e-bay start at 1.0MOD but smaller can be found.

Offline Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #55 on: June 30, 2019, 01:49:41 AM »
Jason--My only knowledge of this type of gears is what is given on the Ebay Website, and there isn't enough info there for me to model them. If they were gears that had been made in North America I could probably have found more dimensional data, or even a 3D model. Even then, a lot of what I do here is "imagineering" and sometimes (not often) I get fooled by the 3D model. If the gears had been expensive, or if I were in a hurry, I would have used them anyways. The gears are very inexpensive, and I'm not in a big rush.

Offline gbritnell

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JRe: Vertical hit and miss engine
« Reply #56 on: June 30, 2019, 04:03:47 AM »
Now it shows why helical gears are used in some situations. Probably a better more compact way to go would be to first reduce to 2:1 with spur gears then use a pair of miter gears to change direction.
gbritnell
Talent unshared is talent wasted.

Offline Jasonb

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Re: Vertical hit and miss engine
« Reply #57 on: June 30, 2019, 07:21:56 AM »
Brian, I would say you have bought 1.5MOD gears (sometimes sold as 1.5M)so should have had enough infore there. If you only know American DP then plenty of conversions on the net that would have shown you were buying close to 12DP when 24DP would have done

http://www.davall.co.uk/media/1877/CONVERSION%20DP%20to%20CP%20to%20MOD.pdf

But a bit more looking around even just on e-bay will find sellers that give some more info. Staying with your 20/40T you could come down to 1MOD or even 0.5MOD. Scroll down these two pages and the seller gives the dimensions at the bottom of the drawings which will give you overall sizes that will be enough to imagine how big they are, further searching of more expensive gear sellers will give full data if needed..

0.5MOD https://www.ebay.co.uk/itm/0-5M-40T-20T-Brass-Umbrella-Tooth-Bevel-Gear-90-Angle-Set-Kit-Ratio-2-1/263035108461?hash=item3d3e1d3c6d:m:mJtwnqYyxAzZVkuMu-vpTHQ

1MOD https://www.ebay.co.uk/itm/1M-50T-25T-Metal-Umbrella-Tooth-Bevel-Gear-90-Angle-Set-Kit-Ratio-2-1/263944017543?hash=item3d744a1687:g:gXAAAOSwiHRboK4m

As a very simple guide if you multiply the MOD by the number of teeth you will get a good idea of the overall diameter of the bevel gear which is actually a little over that. so if your gear were a 1.5MOD 40T it would be a little over 60mm diameter which it looks to be if your cylinder is out of 2" stock. If you really want to calculate it then again plenty of sources for the formula online try this North American one, bevels down the page

https://khkgears.net/new/gear_knowledge/gear_technical_reference/calculation_gear_dimensions.html
« Last Edit: June 30, 2019, 07:31:56 AM by Jasonb »

Offline Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #58 on: June 30, 2019, 01:54:28 PM »
I may try something different here, and actually buy a set of two cast iron piston rings. My previous attempts to make my own have not been successful, so will try a purchased set. However, my Google-foo isn't working very well this morning. Can somebody please recommend a supplier of 1" piston rings in North America. I am ready to make a piston now, but if I do buy a set of rings for it I would much prefer to cut the ring grooves while the piston is set up for turning the outer diameter.---Brian
« Last Edit: June 30, 2019, 02:06:27 PM by Brian Rupnow »

Offline Jasonb

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Re: Vertical hit and miss engine
« Reply #59 on: June 30, 2019, 02:05:48 PM »

 

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