Author Topic: Mercedes-Benz W165 Grand Prix engine in 1:3 scale  (Read 55488 times)

Offline petertha

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #255 on: November 06, 2018, 08:06:09 PM »
Gorgeous work Mike. What are your thoughts behind JB weld on valve cage as opposed to some of the other high temp 'glues' out there, Loctite & such.  Were you after increased viscosity, materials based,  better results from past experience etc?

Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #256 on: November 06, 2018, 08:35:03 PM »
Hello petertha,

Loctite is not a glue, it is a thread locking retainer based on an anaerobic curing acrylic. It cures (sets into a solid acrylic) in the absence of air, the more confined the space, the better it cures. It has no gap filling capability, in fact it may fail to go off, if there is space between the two components.

I considered several high temperature epoxies. I rather liked the look of a silver loaded (powdered silver) high temperature aerospace epoxy because of it's heat conductive properties. Unfortunately it was only available in Jumbo Jet size containers and the price was out of this world. Sorry no samples.

Standard JB Weld has a reasonably high working temperature, due partially to it's high solids content. The cylinders are water cooled, which should keep the cylinder head temperature well within the epoxies temperature range. JB Weld is an affordable and easy to use material with a long working time. It has good gap filling capability, which I specifically wanted for grouting the cylindrical portion of the valve cage and it has a reasonable thermal conductivity.

Fingers crossed that it does everything I hope for. It's too late now, even if I discover a better material

Mike
« Last Edit: November 06, 2018, 09:09:48 PM by Vixen »
It is the journey that matters, not the destination

Offline JC54

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #257 on: November 07, 2018, 12:11:51 AM »
Hiya Mike, I have just read right through this build  :praise2: what can I add that already hasn't been said many times but SUPERB...  :old: :DrinkPint:   Reading the bit about the BRM's took me back more years than I care to count. My late Uncle Eric worked for BRM at Bourne at that time in the machine shop. BRM used to test their cars on an old WW2 aerodrome that is about half a mile away from where I live now. I remember when mum was learning to drive (Austin A40 Somerset) up there, Graham Hill came past us flat out. Mum screamed let go of the steering wheel and jammed the throttle down, Dad struggling to take control.. The A40 was more reliable than the V16 though.   :shrug:     John

Offline Art K

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #258 on: November 07, 2018, 03:06:56 AM »
Mike,
Ah, but the real question is really, Can the JB weld joint imitate a weld fillet? :lolb:
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline petertha

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #259 on: November 07, 2018, 06:56:35 AM »
Loctite is not a glue, it is a thread locking retainer based on an anaerobic curing acrylic. It cures (sets into a solid acrylic) in the absence of air, the more confined the space, the better it cures. It has no gap filling capability, in fact it may fail to go off, if there is space between the two components.

Sorry my bad. I've actually done quite a bit of composites work & 'glue' is a unfortunate slang-ish expression I picked up from others for epoxy, even high end aerospace stuff.
Loctite does specify maximum diametrical gap fill in their literature, for example common ones like 609 = 0.005, 680 = 0.015" along with viscosity & quite detailed temperature/strength profiles. That's kind of why I was asking because I was thinking the max gaps between your threaded components would be quite narrow & possibly favor retaining compounds over higher viscosity epoxy 'adhesive' if that's a safer word. But now that I see the temp/strength specs (680 for example) its not as high as I assumed it was. Even common JB appears to be quite a bit higher although words like 'withstand' isn't quite as rigorous as HDT type properties you might see in typical resin specs. https://www.jbweld.com/collections/epoxy-adhesives/products/j-b-weld-twin-tube

Sorry for the ramble, again beautiful work.

Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #260 on: November 07, 2018, 11:33:15 AM »
Hello Petertha

I did some crude tests before opting for the JB Weld.  I made up three test samples consisting on a 3/8 nut and bolt locked with A) Loctite 638 high strength retainer B) standard Araldite 24 hour two pack epoxy (unfilled) C) standard JB Weld two pack epoxy (high filler content).  The samples were prepared and allowed to set off and cure for a few days. In each case the nut was well secured to the bolt and could not be shifted with a long spanner.

The samples were secured in the bench vice and heated with a propane blow torch. I did not have a thermocouple handy, so cannot say what temperatures were reached. After a few minutes, the Loctite sample softened, as expected, making it possible to remove the nut without much difficulty. The Araldite also softened and  became gummy, allowing the nut to be removed with a little more effort. The JB Weld survived the torch flame for considerable longer. The steel was a beep blue when I eventually got the nut to shift. It put up a good fight and convinced me that it was a good choice for the Mercedes Valve cages.

Other, may have different opinions and achieve different mileage.

Mike
It is the journey that matters, not the destination

Offline petertha

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #261 on: November 08, 2018, 06:22:40 AM »
Thanks for your detailed reply, Mike. I want to integrate your exhaust boss/flange technique for the radial engine heads I'm building. It cleanly solves a lot of issues over the designers configuration of threaded nuts, partial threads, washer seal, lipped tubes... and just plain looks more like the typical FS casting. I didn't have a good feel for JB in this application but this discussion has re-focused my attention. I have some sacrificial head blanks & will do a some prototyping & similar heat test which I'll post separately.The valve cup/cages will probably benefit from the same treatment. Thanks for your patient answers.

Offline zeeprogrammer

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #262 on: November 08, 2018, 03:58:53 PM »
I was just about to complain about the lack of photos and then found the ones at the end of the page. Wow.  :o Awesome!
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #263 on: November 08, 2018, 11:39:15 PM »
Hello Petertha,

The screw-in exhaust boss / flange technique has the advantage that the act of screwing home the exhaust boss brings one half of the screw thread and one mating face into direct metal to metal contact. This has obvious advantages for heat transfer, the epoxy acts as a grout to fill the slight clearance behind the thread, as well as acting as a retainer. The same is true for the screw-in bronze valve cage. The Mercedes valve inserts had the additional complication of a parallel, cylindrical section. I liberally coated the valve guide and the bore of the cylinder head with the stiff epoxy paste which extruded everywhere when I screwed home the valve cage , I felt comfortable that all the void space was filled. I am not sure this would have happened with a thin runny sealant.

JB Weld was the best option I could afford. You may be lucky and find a source of a silver (powder) loaded high temp epoxy.... aerospace or electronics industries? which would give better thermal conductivity. I came across a suitable product (sorry lost the reference) a high silver content epoxy which could be used either; without a catalyst as a non hardening thermal paste, or with the catalyst to provide a bonded joint as well. The product was only supplied as two 1Kg drums. I only needed a couple of spoon fulls.

Now it's your turn, to tell us all about your radial engine.  :popcorn: :popcorn:

Mike
It is the journey that matters, not the destination

Offline petertha

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #264 on: November 09, 2018, 02:40:22 AM »
Now it's your turn, to tell us all about your radial engine.  :popcorn: :popcorn:

Well I don't want to taint your nice W165 build post with my unrelated project. But since you asked I'll attach some 1-time pics to provide a clearer visual. This is my first engine or any machining project of consequence for that matter. Plans are from Ohrndorf. 2 winters ago I built a cylinder stack 'prototype' & told myself if I got that far I would continue on. Last winter I got the crankcase 'middle stuff' done. This winter the goal is to make 5 cylinders for real & take it to completion. So here you can see renderings of the induction tube entering the head & short exhaust stacks coming off a/p design. The valve ports are L-R symmetrical. The hex nut screws into the head & tube is sealed on an inner face by via raised lip, somewhat like I've seen on RC 4S engines. I'd like to do away with as much of the fiddly bits as possible & integrate a JB epoxied aluminum boss with bolt-on flange. Still some issues to sort out as the ports enter at an angle, boss would interrupt some shallow cooling fin features. And I need to pay attention to bolt size & layout pattern for tube mating & removal. So to-be-continued story which I will update elsewhere. Btw my bronze valve cup/guides are not threaded in the head like yours, so that may restrict my adhesive choice. More thinking required. Thanks for your interest.

« Last Edit: November 11, 2018, 02:09:36 PM by steamer »

Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #265 on: January 04, 2019, 12:48:09 PM »
Part 12  Overhead Cam Boxes

Overnight, this built reached a major milestone: 50,000 views. Wow!! that's a lot.   A big thank you to everyone who has called in to check progress and make kind comments. To celebrate, here is a big  progress update for you to enjoy.

Mercedes Benz in Stuttgart were given only eight months to design and build the two W165 cars before their first and only race. The tiny 1.5 litre eight cylinder engines were miniature versions of the much bigger V12 3 litre engines. The bigger engines were cut down from a V12 to a V8 configuration. Many parts had to be reduced in size, but some parts, like the cam shafts and valve gear, were simply reduced in length from 6 cylinders per bank to four cylinders. The result was somewhat ungainly, a huge cylinder head and valve gear perched on top of a block of tiny cylinders.

The next parts to be made were the overhead cam boxes. There are four cam boxes on each engine and they are all slightly different. Each cylinder block has two cam boxes. The inlet side, cam box being a mirror image of the exhaust side, cam box. Also both cam boxes on the right hand cylinder bank are longer due to the stagger of the cylinder bores. With four variations on the cam box design, there was plenty of scope for a cock-up.

I purchased a large slab of 20mm thick aluminium alloy, grade HE30 TF (6082 T6), to make the 8 cam boxes. This material has more than adequate strength and machines well, without the need for coolant. I cut the billet into eight pieces, approximately 200mm (8"0) long by 40mm (1.6") wide using a bandsaw. Because each cam box was slightly different to each other, I decided to machine each cam box individually, rather than as a batch. The first step was to mount the billet in the machine vice and mill out the central pocket down to the level cam bearing seats. Not very exciting but it did produce a lot of chips




The second stage was to pocket out the bottom on the cam box and bore the holes for the eight valves and valve springs




Next, I machined the outer profile of the top flange




This photo shows one of the com boxes with most of the internal detail finished. The top cover bolt holes have been drilled and tapped M1.6, The cam bearing bolt holes have been drilled and tapped M3.0 and the cylinder head bolt holes have all been drilled 2.5mm. You can also see, near the top, where the cam finger follower shaft will lay.




I machined the insides detail all of the exhaust side cam boxes before rewriting the control program to machine the four mirror image cam boxes for the inlet side.




Next the embrio cam boxes were mounted on a jig plate to machine the external profiles. Here the Jig plate is set at an angle to achieve this slopped face.




With all eight cam boxes completed, I turned my attention to making the Cam shaft bearing blocks. I will be using sintered bronze bushings to carry the camshafts. Here you can see the first stage of manufacture. All the bearing blocks have been externally shaped and bolted together as pairs.




The individual bearing blocks are bored to receive the sintered bronze bush and drilled and reamed for the finger fllowere shaft. This simple jig plate ensues that all bearing blocks were machined identically.




With so many cam boxes and cam shaft bearings, it was essential to stamp a serial number on each part to identify it's correct position. Here you can see one of the bearing caps and it's sintered bronze bush. A ground steel bar is being used to align the cam shaft bearings, you can also see the finger follower shaft. The socket head screws are a temporary measure to aid quick assembly, correct size hex head bolts will be used in the final assembly.




Here you can see the dummy cam shaft and bearing assembly beside one of the cam boxes.




Here the dummy cam shaft and bearing assembly are installed within one of the cam boxes and a pair of cam boxes in position on a cylinder block. You can see the valve guides pocking though the base of the cam box.






This final photo shows the result of all that work. Eight cam boxes mounted on four cylinder blocks for the two replica Mercedes Benz W165 engines.

If you ask, "Does CNC make engine building easy?     I will neply, " CNC machining doesn't necessarily make it easy, but it does make very complex parts possible"



Stay tuned

Mike

« Last Edit: January 04, 2019, 01:09:48 PM by Vixen »
It is the journey that matters, not the destination

Online sco

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #266 on: January 04, 2019, 01:10:11 PM »
Fantastically detailed post Mike and some awesome work on show - no surprise that there are so many views.

Best wishes,

Simon.
Ars longa, vita brevis.

Online Stuart

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #267 on: January 04, 2019, 01:20:02 PM »
Mike all I can say is. WOW

Now when I look at my efforts I am even more dissatisfied, not to say they are no good but .......... :slap:

Keep up the good work always a pleasure to see your progress
My aim is for a accurate part with a good finish

Offline steamer

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #268 on: January 04, 2019, 01:28:49 PM »
Great Post Mike!!!! I'm very glad to see this! 

Been in need of a W165 fix for some time!

 8)

Dave
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Offline Jasonb

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #269 on: January 04, 2019, 01:28:56 PM »
Good progress Mike, seems a shame to put rocker covers on the top though I expect you will display one "exploaded" with stand offs.