AOG’s Stuart 10V

[AOG]

Hello everyone, it’s been a while (more than a year) since I posted a build. During my time away I strayed into additive manufacturing and and some gunsmithing but now I’m back and ready to build another engine. I will be building the Stuart 10V.



Just as a note, you will see a lot of 3D printed fixtures and fittings during this build. To be honest, what I have planned is way overkill for an engine the size of a 10V but I am using this build to apply what I’ve learned about additive manufacturing to create useable, printable fixtures for machining. Now let’s get started. The first thing I did was clean up the base casting and flatten the bottom by  rubbing it on a sandpaper covered surface plate until it didn’t rock.



Next the top of the base casting was skimmed flat and the holes were drilled.



Next it was over to the tapping tool to tap the holes.



That completed the base so it was on to the sole plate. First I flattened it on the surface plate and then mounted it to my vise tooling plate. Then I skimmed the top flat . Because of the unevenness of the casting I mounted the part with a 1/4 inch bar through the bearing journals. This helped me to pick up a good center point for drilling the various holes.



Next I added 2 hold downs to the sides before removing the center hold down. Taking a ball endmill I tried to cut the bearing channel. That’s when I hit my first problem. I am always reluctant to crank down on a casting for fear of cracking it. In this case I didn’t tighten it down enough and the part moved while I was trying to mill the slot. I reset and added an eccentric clamp and parallel to the front to stop from moving. Then the cut was completed.



Even with the screwup I managed to get a good fit on the bearing caps.



The part was removed from the vise and the holes tapped.



That completes this first installment. Till next time.

Tony


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[Dave Otto]

Hi Tony
Good to see you back posting a build.

Dave

[crueby]

Nice start on the engine! I've used printed parts a number of times to help keep track of shapes and plan out order of things, not for fixtures yet though, be very interested to see what you come up with.
 

[Mike Bondarczuk]

Hi,

Nice start to the build and I shall be following closely as I have a 10V kit yet to be opened, so will be looking for tips as to order of process and holding fixtures.

Mike

[Chipswitheverything]

Will be interested to see your build ideas.  I recently finished a couple of No 10 verticals, one of which I began as a teenager back in the late '60's ! Made a few bits every now and then, but decided that it was time toactually finish it, still remains to be painted though!
Made a few simple mods to the design to be a little more prototypical, and I found it a very pleasant project to engage with.  Though it is "easy" compared with more major model engineering projects, I thought by the end of doing it, that actually it had required a surprisingly full range of machining techniques to make all the components.  So, quite an interesting little model build.  Dave

[AOG]

Thanks guys, I didn’t have a lot of time this weekend so this one will be short. I spent some time making the bearing caps. First I cleaned up both ends of the extrusion and turned one side of the first cap.



The extrusion was then drilled to 1/4 inch.



The bore will be taken to final size in situ. Next I split the extrusion on the band saw and turned the other side.




The other cap was then turned. Both caps were placed on a fixture and drilled for the mounting studs. I also drilled the center for some PM Research oilers.



The last task for this weekend was to tap the holes for the oilers



Then I hit a snag. The 7BA bolts that I ordered haven’t come in yet.  Since I don’t want to ding up the nice 7BA studs the kit comes with I will hold off on the final reaming of the bearing caps until they come in. I think I will end this with my first family shot.




Before I end this, I do have one question for those of you who have built one of these before. The rounded ends of the bearing caps are asymmetric in length. One side is 1/8 in length and the other side is 5/32. It’s not clear to me what the correct orientation is. Should it be long end facing inside or face out? Thanks for the help.

Tony


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[propforward]

Excellent work as always. I like that multi hole fixture plate - I really must make one of those - looks like a very useful item to have about.

[AOG]

I like that multi hole fixture plate - I really must make one of those - looks like a very useful item to have about.

I’ve been wanting one for years but I couldn’t bring my self to do all of that tedious drilling and tapping. I was looking into designing one and getting it C and Ced when I found out that Saunders machine works already makes one designed to drop into a 6 inch Kurt. It Was only around 70 bucks so I bought one. It’s working well so far.

Tony

[propforward]

Brilliant - hardly worth the time making one for that price. I may have to pick one up!

[Charles Lamont]

Before I end this, I do have one question for those of you who have built one of these before. The rounded ends of the bearing caps are asymmetric in length. One side is 1/8 in length and the other side is 5/32. It’s not clear to me what the correct orientation is. Should it be long end facing inside or face out?

I think you will need the long ends inwards, to control the crankshaft end float, so there should be 5/8" between the faces.

[AOG]

This weekend can be classified as one of those lack of attention to detail hurts shop sessions. I started off by designing and printing some tooling to turn the standard.

I made a couple of different versions to see what or anything would work. Up until now I have been using printed parts only in compression. From past experience, I know that they are weak in tension in particular along the layer lines. I wanted to see if I could print a part that was up to the forces of lathe work by working with the layout direction. I made several different tools with different mounting methods to see if I could make it work. Then I cleaned up and flattened the top of the standard on a surface plate.




Here is one of the final tool designs.



Unfortunately the PLA just wasn’t up to the task. None of my tool designs worked (at least not in PLA).



For each of the designs the support material snapped and the part spun. At that point I put the part on a mandrill and turned the feet in the traditional way.



I took the part over to the mill to clean up the top of the standard and bring it to final height. That’s when disaster struck. I forgot to tighten down the hold downs and this is the result.



I took a big chunk out of the top. Unfortunately there is no saving this part so I am going to order another one.

Till next time

Tony


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[samc88]

Hi Tony, before spending on another one you could always try a jbweld repair on the casting. I've seen people have good results with it in the past


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[AOG]

Hi Tony, before spending on another one you could always try a jbweld repair on the casting. I've seen people have good results with it in the past


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I thought about it but the gouge is in an area that will eventually be drilled for a mounting stud. I was concerned with the drill wandering at the interface between the materials. In any case the replacement casting is relatively cheap and I’m in no rush.

Tony

[Twizseven]

Tony,

Sorry to see your printed parts were not up to the task and you ended up with damaged parts.

Colin

[AOG]

Tony,

Sorry to see your printed parts were not up to the task and you ended up with damaged parts.

Colin

To be fair, it wasn’t the printed parts that caused the damage it was me not properly tightening the hold downs.

Tony