Author Topic: Scaled Hoglet (Jr) project  (Read 86089 times)

Offline Jasonb

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Re: Scaled Hoglet (Jr) project
« Reply #225 on: January 06, 2016, 01:13:07 PM »
I don't think its half size Jo, from what I remember I suggested some odd scale that would allow a nice round figure for either the gears or tehbore, have to look it up when I'm in from work, may have been on HMEM

Offline V 45

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Re: Scaled Hoglet (Jr) project
« Reply #226 on: January 06, 2016, 03:17:26 PM »
Talking with a friend of mine who is making the Spruce Goose engine! ! Ordered some spur gear cutters in 24 & 32  pitch,  going to measure across wires to get the right depth.
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Offline Jasonb

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Re: Scaled Hoglet (Jr) project
« Reply #227 on: January 06, 2016, 04:46:26 PM »
This was the the .431" blank with 20 teeth.

JO 20/40T timing gears 0.589ctrs

0.431" is near as dam 11mm 20Teeth on a 11mm blank is 0.5MOD or a non existant 51.4DP so why are you buying 24 and 32DP cutters?

This also ties in with teh 0.589 center distance between crank and camshaft which is near as dam 15mm

And just to see how the 0.5 Mod can be arrived at, your engine is 0.625" bore, the original was 1" bore.

When scaling down the DP of the gear is reduced by teh same amount, original gears were 32DP

32 x 0.625 = 51.2DP

So you are either going to have to make your own cutters as Ausdier  drew or if buying cutters then get 0.5MOD
« Last Edit: January 06, 2016, 05:20:11 PM by Jasonb »

Online Jo

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Re: Scaled Hoglet (Jr) project
« Reply #228 on: January 06, 2016, 05:27:55 PM »
JO 20/40T timing gears 0.589ctrs

:headscratch: A 20 Tooth 32DP gear has a pitch diameter of 0.625, A 40 a PcD of 1.25, add them together and half them and you get the 0.928 between centres. Where does the 0.589 come from   :noidea:

Dave can you confirm what scale this is in and the distance between centres.

The 48DP  30/15 is an elegant cheap solution for a half scale engine the gears are less than £7 for the pair.

Jo
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Offline Jasonb

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Re: Scaled Hoglet (Jr) project
« Reply #229 on: January 06, 2016, 05:36:56 PM »
It came from a post on HMEM where V45 gave the details.

Full size hoglet model has gears as you say at 0.928, working at a scale of 0.625:1 this engien will be

0.625 x 0.928 = 0.589 ctrs

15/30 48DP is not a lot of good as the ctrs will only be 0.469, 20/40 48DP would be closer but as the frames are already made 0.5 MOD is teh best bet
« Last Edit: January 06, 2016, 05:43:14 PM by Jasonb »

Online Jo

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Re: Scaled Hoglet (Jr) project
« Reply #230 on: January 06, 2016, 05:41:03 PM »
Ok so make an eccentric bush and increase the distance to 0.594 imperialous measures and use a 38/19 tooth 48DP gear pair (still £7 for the pair  ;)).

Jo
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Offline Jasonb

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Re: Scaled Hoglet (Jr) project
« Reply #231 on: January 06, 2016, 07:59:24 PM »

Offline V 45

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Re: Scaled Hoglet (Jr) project
« Reply #232 on: January 08, 2016, 12:27:12 AM »
I got lost in all the gears as they were going to be made towards the end. That's where I'm at now. I recall Jason you mentioning those gears prior. I had forgotten about it...3 years ago ! I'll order one of those cutters .5 module. Not going to get too much done over the next few weeks. Let you know when back at it. The cam will be the next BIG issue !!
  Thanks again !!
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Offline Jasonb

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Re: Scaled Hoglet (Jr) project
« Reply #233 on: January 08, 2016, 07:28:49 AM »
You don't need just one cutter you need two as the tooth profile alters depending on the number of teeth on the gear wheel.

Offline Graemep

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Re: Scaled Hoglet (Jr) project
« Reply #234 on: January 08, 2016, 11:20:10 AM »
Hi V45 I  built the hoglet (jr) in 6:10 scale about 18 month ago. When  I decided to scale down the Hoglet the first thing that I did was to find what bearings and gears
will fit . So when I redraw the hoglet I adjust the centres ,shafts and bores to suit standed gears , bearing and harware.  Now to your problem as Jasonb said .5 module
20/40 tooth gears should fit .589 centres .  You may have to play around with the depth of cut when cutting the gears and yes you will need two cutters, or look up
cutting gears with a stright hob and make your own hobs. Looking at at your single point gear cutter in your previous post there seems to be a few thing to look at 1,centre hight 2,the cutter looks blunt  3,the cutter looks like there is no back clearence and is rubing.  Anyhow the build so far looks excellent and I am sure you will get there
soon.

  Graeme

Offline V 45

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Re: Scaled Hoglet (Jr) project
« Reply #235 on: February 01, 2016, 01:49:01 AM »

Thanks for all the replies with the gear issues !!! Well, for now they're on the back burner AGAIN !! It's becoming an awful attempt at a model engine...soo moving on.

Today I started on the carburetor bits. Here's a few pics of the process. Those of you that can cut a .055" fuel needle in one pass I salute you. This was the 6th and final attempt after all of them had bent over in the collet !! After those futile attempts and almost turning into another back burner... I decided to try it in steps. That seemed to work out fairly well. The parent stock is .109" drill rod, I don't have any small stainless steel. I wasn't turning 1/2" stainless down that far !! The actual needle section is turned down to .055" with the back section .104". The fuel jet body is 1/4" brass with 8-32 threads at each end and a 1/8" fuel line adaptor. I milled a contour into the brass fuel line with a 3/32" end mill. The fuel end of the jet assy has a .036" hole drilled.









All that is left is to silver solder the bits together. That will be another adventure !! I'll be asking questions on that. Stay tuned for pickle and such questions.


I also attempted to make the carb intake breather :(
I started with 1" brass turned to .938". Put a 22 degree taper in the bore, used a parting tool to get the overall length plus .015" for clean up after. Then to the mill for hole drilling 2 separate 8 hole pitch circles. Then back to the lathe to finish the back side. Mis-calculated the plunge cut and scraped the part by .015". So another practice part !








Better luck next time !! At least a few good parts today. The struggle continues.
Until next time...
 V 45


 
« Last Edit: February 08, 2016, 12:46:30 PM by V 45 »
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Offline V 45

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Re: Scaled Hoglet (Jr) project
« Reply #236 on: February 02, 2016, 03:30:52 AM »
Well a good part tonight ! I went at it a different way. I drilled all the holes first on the mini mill before turning in the lathe. It worked out much better. I now had a reference for the center taper. I had to use smaller drill bits on the 1st attempt since the taper was too big. I could tell by looking at it they would cut thru the taper when I brought the drill bit closer to the work piece. I used the correct size drill bits according to the print on this second attempt. It's also thinner like it should be. I just finish the 1st one all the way since it was already SCRAP !!  This one looks pretty good...polished this one as well. The carb intake is next...4 jaw chuck time !!

Thanks again...

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Offline V 45

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Re: Scaled Hoglet (Jr) project
« Reply #237 on: February 08, 2016, 02:13:51 AM »
A little more in the dungeon .... more carb parts started. The 1st picture is the scrap lump the carb body started as...


After cutting down to size...figuring out the layout and trying to my head around the part...


After layout spot drilling, drilling and tapping holes... Yepper had to mark top and bottom !! Didn't want to get lost and drill wrong size holes...


Tapping all the holes before moving to the lathe. Neither my mill or drill press have enough Z height to use the only tap guide I have. So I quickly looked for something else to use...a small round piece of 1/8" brass and added a slight taper to fit my tap handle used a only a light pressure to align the tap...a 2-56 tap in this picture.


After tapping put the part in the 4 jaw to do one end of the turning, then a little polish. It's Super Bowl time so the rest of the turning will have to wait. I have to put a 22 degree taper in this end and the other will have a 16 degree taper.


This I had started this yesterday... this is the intake manifold...once to size, drilled and reamed, next to the lathe


Four jaw chuck getting the part set up. Here I'm using a length of drill rod I had put a point on to find my mark.


Turned and now getting ready to drill through...
 

Once drilled I put the o-ring groove in...


Then polished...


Until next time...Thanks again for looking. 

« Last Edit: February 08, 2016, 02:24:31 AM by V 45 »
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Offline V 45

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Re: Scaled Hoglet (Jr) project
« Reply #238 on: February 10, 2016, 02:12:05 AM »
Here's the body of the carb...
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Offline zeeprogrammer

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Re: Scaled Hoglet (Jr) project
« Reply #239 on: February 10, 2016, 02:18:26 AM »
Prove to me that's not one of those fake pennies.  :Lol:

Looks excellent.

The carb. Not the penny. The penny is practically worthless.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Zee-Another Thread Trasher.

 

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