Author Topic: 30cc Flat Four (Puma)  (Read 2353 times)

Offline doubletop

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Re: 30cc Flat Four (Puma)
« Reply #30 on: July 03, 2019, 10:33:07 PM »
When I buy bearings I use SMP bearings in Carlyle st Christchurch, their prices seem ok.
Ian S C

Maybe it’s the case that in the past NZ suppliers that offered a reasonable price were not obviously online so you couldn't find them. Or they have woken up to the fact that if they want to stay in business, they need to offer their products at an internationally competitive price. Hiding behind, "NZ is a small market" and "Shipping costs to NZ are high" just doesn't work anymore.

In my early days of this hobby I was looking for a something from Vertex. The best price I could get, landed in NZ, was from the UK. Ridiculous when the item was being shipped from Taiwan to the UK and then to NZ. In the end I found the Vertex importer and cut out the middle men, even then it was a similar price to getting it from the UK.

Pete
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline Ian S C

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Re: 30cc Flat Four (Puma)
« Reply #31 on: July 04, 2019, 01:16:41 PM »
Got my 6" Vertex rotary table with dividing plates and tail stock in Christchurch, and direct from Taiwan about the same time as I got my lathe, also from Taiwan, through Paykels, now I think Blackwoods Paykel
Ian S C
« Last Edit: July 04, 2019, 01:24:01 PM by Ian S C »

Offline doubletop

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Re: 30cc Flat Four (Puma)
« Reply #32 on: July 05, 2019, 08:51:05 AM »
Got my 6" Vertex rotary table with dividing plates and tail stock in Christchurch, and direct from Taiwan about the same time as I got my lathe, also from Taiwan, through Paykels, now I think Blackwoods Paykel
Ian S C

Ian

The heavy stuff I  do purchase locally, lathe and mill. I got my Vertex rotary table direct through the NZ importer. A request to Vertex in Taiwan gave me his details. He didn't have stock, but I ordered anyway. It to only 4 days to arrive to me

Pete
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline doubletop

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Re: 30cc Flat Four (Puma)
« Reply #33 on: July 05, 2019, 08:52:30 AM »
A bit of an update

The cams were completed and case hardened with “Cherry Red” case hardening compound.



They’ve now been parked ready for the assembly of the camshafts, which I’ll do once I’ve got my head around it and confirmed the firing order and done the timing diagrams. I’ll do it all at the same time.

Next up was the crankshaft. I’m doing a built up crank the same I did with the Bobcat. I forgot to take a photo of the separate parts for the this crank so here they are for the Bobcat.



Here’s the Puma crank with the parts just pushed together.



And assembled with high strength Loctite 680



I assembled the cranks and webs first to get them into alignment and used the lathe to ensure the nose and tail were in alignment. Next will be drilling the webs and inserting pins to make absolutely sure it all stays together.

The next parts are the four conrods. I started on the blanks while I allowed the Loctite to cure.

I recently saw somewhere a suggestion to use a lathe tool in a fly cutter.  With a CCGT060204 ceramic tip the results were outstanding



So now  have four blanks ready for the next stages.




Pete
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline Roger B

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Re: 30cc Flat Four (Puma)
« Reply #34 on: July 06, 2019, 10:35:07 AM »
Just catching up with this after having been away on holiday  :)  :)  :ThumbsUp: Looking good  :praise2:  I'm not sure of the need to mill the cams in 1° steps unless you have CNC. I have used 6° steps without problems.
Best regards

Roger

Offline doubletop

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Re: 30cc Flat Four (Puma)
« Reply #35 on: July 06, 2019, 10:38:35 AM »
Just catching up with this after having been away on holiday  :)  :)  :ThumbsUp: Looking good  :praise2:  I'm not sure of the need to mill the cams in 1° steps unless you have CNC. I have used 6° steps without problems.

Roger

You are probably right, and Malcolm suggested going in 2deg steps, but I wasn't going to try it and then wish I hadn't and have to start again.

It just added a few extra hours to the job as I was making two sets.

Pete
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline Laurentic

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Re: 30cc Flat Four (Puma)
« Reply #36 on: July 06, 2019, 12:38:06 PM »
Pete, just out of interest, when you loctited the crankshaft together what clearance did you allow between pin/shaft and relevant bore in the web?  I was thinking too much and it's a weak joint, too little and then no space for the loctite?
Chris

Offline doubletop

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Re: 30cc Flat Four (Puma)
« Reply #37 on: July 06, 2019, 10:42:48 PM »
Pete, just out of interest, when you loctited the crankshaft together what clearance did you allow between pin/shaft and relevant bore in the web?  I was thinking too much and it's a weak joint, too little and then no space for the loctite?
Chris

Chris

It will be about 1 thou. The tail is 10mm ground silver steel and the hole was reamed. Since being glued I've now drilled the webs 2mm and inserted 2mm pins through all the joints. I did the same for the Bobcat and then for the crank for my 7.25" guage Dart. None of them have been a problem



Pete
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline Laurentic

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Re: 30cc Flat Four (Puma)
« Reply #38 on: July 06, 2019, 10:47:29 PM »
Thanks Pete, the 0.001" clearance and 2mm pins were what I was thinking would be about right!  Good to have it confirmed....

Chris

Offline Brian Rupnow

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Re: 30cc Flat Four (Puma)
« Reply #39 on: July 07, 2019, 12:05:39 AM »
Loctite has a product that is used with press fits. I see a lot of people on the forums who think that you have to leave some clearance on fits so as not to scrape the Loctite off during assembly. Loctite claims that you don't need to leave any clearance. I don't leave any clearance on fits (not intentionally anyways) and I've not had anything come apart.

Offline doubletop

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Re: 30cc Flat Four (Puma)
« Reply #40 on: July 09, 2019, 08:05:23 AM »
Conrods done

Before and after zapping in the sand blaster to remove the tooling marks






Time to roll the dice again and decide what to do next

Pete
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline Laurentic

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Re: 30cc Flat Four (Puma)
« Reply #41 on: July 09, 2019, 12:25:10 PM »
Interesting comment Brian, must admit I was in the camp that thought a very wee clearance was required before using loctite.  Do you have the loctite number for press fits, I will get some in!   :ThumbsUp:

Nice piston rods Pete.

Chris

Offline Brian Rupnow

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Re: 30cc Flat Four (Puma)
« Reply #42 on: July 09, 2019, 01:35:13 PM »
Top Pick LOCTITE 620 is a high temperature (450 degrees F), high viscosity liquid retaining compound. Provides a shear strength of over 3,800 psi on steel. Locks and secures metal cylindrical assemblies up to 0.015' diametral clearance. Prevents metal fretting and corrosion. Seals against leakage. Recommended for high temperature retaining of parts with a clearance or interference fit, i,e, retaining bushes, bearings, seals, fans and liners. Requires heat cure to achieve temperature resistance. ABS Approved.
This and Loctite 680

Offline Laurentic

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Re: 30cc Flat Four (Puma)
« Reply #43 on: July 09, 2019, 06:07:33 PM »
Thanks Brian, Loctite numbers noted down!!

Chris

Offline doubletop

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Re: 30cc Flat Four (Puma)
« Reply #44 on: July 09, 2019, 08:56:44 PM »
Top Pick LOCTITE 620 is a high temperature (450 degrees F), high viscosity liquid retaining compound. Provides a shear strength of over 3,800 psi on steel. Locks and secures metal cylindrical assemblies up to 0.015' diametral clearance. Prevents metal fretting and corrosion. Seals against leakage. Recommended for high temperature retaining of parts with a clearance or interference fit, i,e, retaining bushes, bearings, seals, fans and liners. Requires heat cure to achieve temperature resistance. ABS Approved.
This and Loctite 680

Agreed

The loco cranks were done with 620 and the Puma with 680

One of the benefits of 620 is the slower cure time so you've got a bit of wiggle room. The job doesn't lock up almost immediately on assembly. It gives you time to get it all together and into any alignment jigs you may be using.

Pete
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss