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My Workshop / Re: Bill's Shop Renovation
« Last post by b.lindsey on Today at 03:18:24 PM »
Kim,

The compressor is in the closet as shown on the attached PDF file. Currently in addition to the plumbed outlets shown yesterday, there is a plumbed outlet overhead just to the left of the mill as well. I may look at extending this over the area where the Sherlines will reside also as another drop connection from overhead.

Bill
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Specific Engine Help / Re: Small capacity diesel engines
« Last post by Jo on Today at 02:15:20 PM »
Alpha was one of those centre page pull outs in ME Mag number 4027

Jo
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Machines, Tools and Fixtures / Re: Helical gear cutting
« Last post by gbritnell on Today at 02:13:20 PM »
Hi Andrew,
 I'm certainly no gear expert, I just have read and studied making gears for quite awhile so I'll try to explain the helical gear conundrum as best I can.
First of all you are correct in stating that the tooth and space of a spur gear are equal at the pitch circle. So let's take that a little further. Gear teeth are formed by the involute curve, that is no matter what number of teeth are on the mating pair they have a smooth rolling transition as they mesh, from rack to 13 teeth. There are 8 cutters per pitch to create the proper involute curve for each tooth count. Now I have never tried it but I'm assuming that from your statement of equal tooth width and spacing if you cut 2 gears with the same tooth count but used different numbered cutters on them the width and space would be the same at the PD. The difference is they wouldn't roll together smoothly because the mating tooth profiles is incorrect. I hope that makes sense.
 Now onto helical gears. Here again going back to what you stated, tooth width/spacing being the same, helical gears are the same as spur gears in that respect. Now I will try and explain what is happening. Let's say that you set up to cut a helical path on a shaft but for the sake of explanation you use a woodruff key cutter to cut the groove. Given the diameter of the cutting head and the helical path it is traveling the sides of the groove will be splayed out. (wider at the top) The only way to cut an exact profile would be to use an end mill that was ground to the tooth profile and the cutting action was directly at the point of contact. This is impractical so involute cutters are used.
Now we know that each involute cutter in the set has a different profile and that cutting a helical path on a shaft with a large diameter cutter will produce a splayed slot we choose a cutter from the set that compensates for the splayed cut. There is a formula for finding NTCS (number of teeth for cutter selection) which is NTCS=NT x cube of the secant of the helix angle. There are charts that simplify that math.
The bottom line is the tooth and spacing for a given pitch are equal at the PD. it's just that you have to use the proper cutter to get the correct tooth profile for a given tooth count.
 I have two free books that I downloaded years ago, one is a U.S. Navy machinists book the other is A Treatise on Milling by the Cincinnati machine company. Each of them cover gear cutting to the point that your head starts swimming but the basics are there and for the hobbyists it helps to explain how to cut gears more effectively.
gbritnell
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From Kits/Castings / Re: Stuart No 1
« Last post by Chipswitheverything on Today at 02:06:44 PM »
Your engine is coming on very well Jo, and quite rapidly!   i liked the neat and simple surface plate arrangement for determining the marking out of the column foot from the crosshead guide.  The chunks of the No 1 are hefty enough to give the feel of doing a bit of "proper" engineering, I thought so anyway!   Dave
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Specific Engine Help / Re: Small capacity diesel engines
« Last post by Ramon on Today at 02:02:40 PM »
Yep just had a check Neil  :ThumbsUp:

There was a series of articles in Model Engineer by a Richard Gordon on his 'Alpha' .5cc side port diesel.

Unfortunately there's no dates on the pages so don't know when it was featured - in the nineties or a little later perhaps - maybe Jason can help here.

It's a nice little engine with full coverage of the build though you shouldn't need that 'I'd a thought'

Whatever, I have hard copies which I can pass on should you want.

Regards - Tug


Edit - Didn't Chris Boll do a .8cc? the 'Boll-Aero' - or was that 1.8cc
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From Plans / Re: Southbend lathe engine
« Last post by GordonL on Today at 01:55:05 PM »
FYI  I was curious about that book and tried searching for it and found that the book can be downloaded for free.

http://vintagemachinery.org/pubs/detail.aspx?id=16819
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Vehicles & Models / Re: Chris's Marion 91 Steam Shovel
« Last post by crueby on Today at 01:54:33 PM »
Engines reverse in quick order!!  :cheers:


The engine is running at constant forward speed throughout this test, I was moving the clutch lever to control the raising and lowering of the bucket. The engine throttle valve has not been made yet so it was just turned on to around 15 psi at the compressor.


I did test it last night with the tracks, could only move 6 inches on the table but it had plenty of power to move, the gear reduction to the track is 20 to 1. Very happy with the runs, now a bunch of little cleanups, paint touchups, and reassembly. Need to make the last gear guards too, then on to the slew engine.


Thanks all!!   :cheers:
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Vehicles & Models / Re: Chris's Marion 91 Steam Shovel
« Last post by kvom on Today at 01:43:44 PM »
Engines reverse in quick order!!  :cheers:
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Specific Engine Help / Re: Small capacity diesel engines
« Last post by Ramon on Today at 01:43:07 PM »
Yes that's right Jason ten times bigger  ;D - I've rebored down to .5cc but not made one Dave

Neil - I have a copy of the plans book mentioned (CD) though I have a feeling it won't allow direct copying.
There is a very nice 1cc diesel - the Weaver/Ransom - that could be slightly reduced and it's easily made from bar stock too. I believe many have been successfully made and are good runners -ideal for free flight. There's also the Deezil 1 (2?)cc side port that you could do the same to.

Not sure but there may be plans on Ron Chernich's Model Engine News site that is still extant

I also think I have  drawings for a .8cc from Model Engineer on file somewhere

I would imagine you can find a copy of the Motor Boys Book 'down there' but if not let me know and I'll see what I can do to help

Tug
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Specific Engine Help / Re: Small capacity diesel engines
« Last post by Jo on Today at 01:40:25 PM »
0.5cc Compression Ignition Engines are very common.

This is a design my friend John Carter did, I have a casting to make one  :)

Jo
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