Author Topic: 1/3rd Scale "Ball Hopper" Monitor  (Read 28823 times)

Offline Roger B

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #30 on: May 27, 2014, 07:41:49 PM »
Looking good  :ThumbsUp:  :ThumbsUp: I hope you have more success starting it than Jo has had so far with her infernal combustion engine  :mischief:
Best regards

Roger

Offline roughcaster

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #31 on: May 27, 2014, 08:19:56 PM »
good to see more progress Jason, am taking note of all these set ups

Offline Don1966

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #32 on: May 28, 2014, 12:42:10 AM »
First rate work Jason still enjoying following along.


 :popcornsmall:

Don



Offline Jasonb

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #33 on: July 20, 2014, 07:14:58 PM »
I think another installment is long overdue :embarassed:

The flywheels on the Baker engines all had five spokes which makes them a bit hard to hold using my preferred method of the 4-jaw chuck bearing on the inside of the rim and the 3-jaw fits no better so I had to go with a faceplate. This is not quite so straight forward as there are a couple of protrusions on the spokes which are part of the governor workings so I had to use a disc of MDF between the faceplate and flywheel with suitable holes to clear these and the hold down bolts.

Here is the first side being done, firstly I lightly faced and centre drilled the waste in the middle where there was extra material. The live centre then gave a bit more support while the rim was machined.



I then bored the hole to a nice fit on the crankshaft and also skimmed down the outside of the waste before turning the flywheel over to do the other side



Due to the hold down bolts I was only able to face back the three bosses that take the drive pully so had to hold  the 3-jaw to cut the step that locates the pully rim, I knew that waste material would come in handy ;)



The engine is balanced by grooves cut on the inside of the rim with a 7/16 ball ended cutter, these are quite pricy in metrificated England so I went with an 11mm one at about 1/3rd the price and I doubt the 0.005" difference will matter. It was a bit hairy using my 6" rotary table with the 9.5" flywheels due to the ovehang and backlash but the cuts turned out OK in the end. The rim is just rubbing on that angle plate to stop it deflecting under the pressure of the cutter.





The castings have some rather rough nuts and bold heads cast into them, rather than try to clean these up I cut them off, filed the face flat and ground a shallow hole. Then I made up some dummy ones from steel with a short spigot on the undersides so they could be bonded into the hole with JB weld, looks like I also made the needle valve that day.





Unlike the Monitor kit that Maury sells this one did not come with a pully so I fabricated it. Starting with some ERW tube and a few off cuts of 1/8" steel suitably shaped (freehand on the belt sander) to the inside curve these were silver soldered together.



The holes were then drilled at the same setting as the ones in the flywheel so they would all line up OK



I then set the flywheel on an expanding mandrel and used that to hold the pully while it was trued up and the outer face crowned



The rotary table was centred on the mill spindle and then each mounting lug in turn centred to the mill and rounded over.



And the finished pully, I've left the inside a bit rough as its supposed to be a cast surface.



That will do for now, I'll try not to leave it so long until the next installment, J.

Offline maury

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #34 on: July 21, 2014, 02:13:38 PM »
Jason, very nice work on the "other" Ball Hopper Monitor. In your flywheel picture, it just may be the picture, but it looks like you are turning the OD at a high rpm. Can you give some details about rpm & feed. I find that to get a really nice finish in CI I need to slow the RPM way down, cut the feed to about .0005, and use HSS tooling, then go have a beer.

maury
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Offline Jasonb

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #35 on: July 21, 2014, 05:22:21 PM »
Hi Maury, as I have one of the far eastern 11x27 lathes with the variable speed DC motors they do tend to loose a bit of torque when the speed is very low combined with large dia workpieces. On say a 9" dia casting I can stall the  spindle if I take much more than 0.025" depth of cut.

I tend to get round this but running at a faster speed which also gets the motor fan doing some cooling and take a few more slightly shallower cuts, works out about the same amount of machining time in the end as teh cut takes less time but more passes are needed.

I tend to use carbide inserts on CI with the exception of the last few passes when boring cylinders or liners as I find HSS does not spring away from the work as much as the inserts. Those Monitor wheels have quite a few cavities/inclusions particularly on the side of one wheel so I don't think HSS would have stood up too well anyway.

Can't remember off hand what speed I was running but likely to be 275rpm, 0.020" depth of cut and a feed of 0.002/rev. This is a video of teh slightly larger Galloway engine at 10.2" at 250rpm, the rest as above

[youtube1]http://youtu.be/s2kPSYxB8cQ[/youtube1]

Offline maury

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #36 on: July 21, 2014, 06:21:22 PM »
Thanks Jason, I think your speeds are in the same ballpark as mine. it just looked faster from the picture. I lucked out and found an old Calusing 12" in good shape. I put a VFD on it, and can get a wide range of speeds.

 I'm sure you didn't have to pay extra to get those inclusions, but I don't offer them even for free. I have the foundry use ceramic filters in my molds, they clean all the slag out before it gets past the sprue.

maury
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Online Jo

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #37 on: July 27, 2014, 07:57:25 PM »
 :headscratch: Now normally when there is an F1 race on the tv Jason gets around to writing up the next instalment on his engines but today nothing  :shrug:

And now on their 4 week summer break so does that mean no write ups for another 4 weeks :(

Jo
Enjoyment is more important than achievement.

Offline Jasonb

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #38 on: July 27, 2014, 08:05:44 PM »
All that dancing tired me out  ;) :pinkelephant:  :cartwheel: :pinkelephant:

So you will have to wait, anyway I was not that boring a race so no time for typing

Offline Alan Haisley

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #39 on: July 27, 2014, 11:17:44 PM »

The castings have some rather rough nuts and bold heads cast into them, rather than try to clean these up I cut them off, filed the face flat and ground a shallow hole. Then I made up some dummy ones from steel with a short spigot on the undersides so they could be bonded into the hole with JB weld, looks like I also made the needle valve that day.


Jason,

Looking at this picture got me thinking. Did the original engine have a through bolt there with a "bite" taken out of it by boring out the hub with the bolt in place but not drawn up? To grip the shaft the bolt would then be drawn up. It works on some gauge mounting clamps to hold on to bars, would it work here too?

Alan

Offline Jasonb

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #40 on: July 28, 2014, 03:15:38 PM »
The original actually has a split hub so the bold pulled it tight onto the shaft by closing up the hole, On most models its suggested you don't split the hub as there is not really enough strength in the smaller bolts to close up the bore. Also the bolt just misses the bore, not easy to see from that photo.

But yes I have seen that type of cotter used where a segment is cut out to match the shaft as as the cotter is pulled sideways it grips.

J

Offline Jasonb

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #41 on: August 17, 2014, 06:21:03 PM »
With that bits that go onto the ends of the crankshaft done I though the next logical parts should be what goes in the middle.

The conrod is supplied as an iron casting with another casting for the bearing cap, one unusual feature is that the cap is pivoted much like a hinge on one side with a single bolt to the other as there is only access into the crankcase from one side.



Making use of a step in the casting halves and the machining allowance at the other end the main rod was taken to width and a light skim taken along its length so I could hold it by the "I" section if needed.



Luckily the ends just fitted in the vice so held by them the central part of the hinge was milled to width, then the part reversed to take the face back to the joint line.





The bearing cap was machined in much the same way adjusting the hinge gap until it fitted snugly onto the conrod.



Then using a G clamp to hole the two halves together, the vice to stop it all moving about and some 1-2-3 blocks for support the hinge pivot hole was drilled and reamed.



With a length of silver steel (drill rod) as a temporary hinge pin the hole for the bolt was then drilled with the job held to an angleplate with assorted clamps.



Now I could make use of the skimmed side of the "I" beam to support the rod while the little end was drilled and reamed and at the same setting a boring head was used to open up the big end to 3/4"ready to take a bearing.





Finally a bit of hand filing to clean things up and a quick whizz around in the rotary table to make the big end look a bit more presentable.



The big end bearing was made in much the same way as the others, tin two bits of bronze, sweat together and then machine.



The small end bearing is just a simple turning gob and then pressed into the casting and thats another part ticked off the list



J

Offline smfr

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #42 on: August 17, 2014, 09:01:16 PM »
Very nice, Jason. I haven't seen a conrod with a hinged head like that!

Should there be some space opposite the hinge to allow adjustment of the bearing fit?

Simon

Offline Jasonb

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #43 on: August 17, 2014, 09:05:35 PM »
I did toy with the idea of adding a shim while machining but decided that its unlikely the engine will get enough use to need the bearing redoing and if it did a quick lick with a file on the iron would sort it out. Also as there is no provision for a lock nut I wanted to do the bolt up tight.

J

Offline Don1966

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Re: 1/3rd Scale "Ball Hopper" Monitor
« Reply #44 on: August 17, 2014, 10:28:27 PM »
I see your all rested from the dancing and made some more progress Jason. It's always nice to see your updates.  :ThumbsUp:

 :popcorn:

Don

 

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