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I have never made Brass name plates before so thought why not give it a try. Although as I do not have access to a laser printer I purchased some transfer paper from a local electronics shop which is used to make PCBs which stated laser or photocopier. So printed some Howell logo's out using a photocopier and ironed it onto some 1/16" brass plate. The etch has gone 60 minutes in warm ferric chloride I should probably finish it up however thought I will give it another 30 minutes. The Howell stencil which come with the plans had very very thin characters which did not transfer that great so simply chose a font and did my own for now. As you can see in the pic the toner has stayed on quite well. & yes Ill remeber to stick it on the front of the radiator :) I do really like the Howell "red" however think I will simply be different and go blue.
That name plate looks great on your lovely radiator 👍
Did a little bit of "watching" this weekend whilst my CNC router did its thing to the radiator support model. I am not considering converting my Mill (optimum BF20)to CNC however my little CNC router table does a reasonable job as long as I dont need a tall Z. One day I do plan an upgrade to linear rails and a better bed however it does OK at the moment . The 1.5KW air cooled spindal has no issues with aluminium however obvisouly not up to steel or I assume brass (never tried) So I leave the harder materials to the manual mill.
I could not imagine doing these supports on the manual mill. So the router can take care of the supports and mounting rails this week. I will think about making a holding jig for the rocker arm brakets, rockers and the knife&forks end rods...These may be a combo of manual mill and router.

Anyhow a pic of my little CNC router doing its thing. Im sure you will believe me if I say I never leave the allen key in the hold down screws, oops !


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When I was in machinist school in the military they would make someone wear a huge chuck key around their neck if their hands were off the key for the chuck of the lathe and they had left it in.
Rob, is that CNC router your own design?

If you google “workbee cnc” thats what the frame is modelled from. Another one is “ox cnc”. Then its up to you on motion, software and spindle choices. This unit limits z height to provide better rigidity however i may machine some 1/2” thick side plates another 1” taller for Z. I made it 5 years ago ~us$1200 including the spindle and drive. Aliexpress parts, however notice pricing has increased alot lately.

I now use a 5mm end mill and use adaptive clearing which cuts full pocket depth at 2mm load / 750mm/min so is quite quick for these smaller parts and provides reasonable sized chips.

Time to clean up the supports and paint their inserts and start on the radiator cowling.


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Another element ticked off the list. Awaiting some silicon tubing so I can do a pressure test however visually the soldering of the cores and tanks looked good under the magnifying glass. However a mounting screw in the lower tank has penerated the the interior of the lower tank, so will need to put a little loctite sealant on that screw on final assembly. I tried to bead blast the cowling, looks a little like undercoat grey however think it will all blend in when I also blast the block and there are a few more pieces with that finish. After bead blasting I put a little penetrating oil sealer on it (the sealant that comes with black oxide) which dried and now stops the greasy finger prints.


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Have not updated for a couple of weeks and wish I had made more progress. Although have ordered some drills for the carby jets and looking at upgrading my cnc router to better handle two sided machining.

Machined the rails and took too long to make two silly little brackets for the radiator mounts. Surprised how rigid the radiator is when mounted by a couple of small screws. Now its on the rails it motivates me to keep adding parts. Only 2 years to go I think….


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Nothing ventured nothing gained, I was getting some high quality resin 3D prints done for another project and stumbled across the fact that I can get SLM aluminium parts printed. I wanted to give it a shot so have sent off the Howell v4 inlet manifold (thanks @scooby )to get printed/fabricated or whatever you call it ! I added a some tolerance to all the flanges in a hope I can machine them to fit. Time will tell if it meets expectations however besides freight costs the cost I thought was quite reasonable.

There is enough to fabricate myself on this engine build so have no issue in a little helping hand…. Shame the castings are no longer available direct from Howell however this metal printing could be a good option in 2022.

Might not work out and I fabricate it myself which will also be ok although a touch disappointing

Anyone had experience with SLM parts ? Trust I can face the flanges reasonably well on the mill.


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I think from memory it needs a min wall thickness of 1mm for metal printing. Now the cost of the radiator I think would be beyond an acceptable cost, for me at least. I can only guess at ~$450 as it must be 8x more material than the inlet manifold. I dont have a step file to upload of the radiator to get priced. However any model file you can simply upload online for an instant price. When you commit they review and provide final costs. For the inlet manifold online they stated $49 then when they reviewed, it went to $47 then they gave me a $5.00 first time discount, so the part itself was only $42.

However I have noticed though they have more traditional 3Dprint good for 187 degC using a special resin which is very cost effective. The qualitity I have seen of the resin prints looks like its injection molded. So if I hadn't already made the fan cowling I would of got that resin printed for sure. The only other part Im considering getting resin printed is the fan assembly as I think I could model a nice filleted blade assembly that bolts onto the pulley. The oil gallery at the front of the engine is another aluminium SLM candidate as I could form this piece alot nicer than its square edged fabrication part in the plans. This gallery is the oil filler as well so could extend the gallery to form a oil filler neck etc.
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Just a small update. Purchased a (1 tonne) arbor press to install the valve cages into the head. When I tried to press the bearings onto the cam shaft I cracked the small bearing flange so thought a press will help future assembly of the camshaft as well.

Small update to the heads below whilst I await the inlet manifold to be printed. I have not machined a valve seat as yet. Ill make a cutter in the future.


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@bluejets Ohh Something i should keep in mind

Without loctite you could slip then in, nearly by hand ! however with a smear of loctite they needed a little more persuasion.

Hope they will be ok however at least with a press they went in straight which I was most concerned about. Point taken though, thanks
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I reamed the holes in the head 13/32 (.40625) and made the valve cages .406 like the plans say. I recall just putting green loctite in the two grooves ( and maybe a little bit between them) I put the head on a flat surface and pushed valve cages so it would be flush with the bottom of the head. Then wiped any loctite that got squeezed out
Wow wow….. cannot believe how well the inlet manifold turned out.. SLM printed in aluminium. I ran the face across a file and the flanges are going to machine very well I think.

I plan to use 4 threaded studs and washer/nuts for the top carby mounting.

The surface is so uniform its a thing of beauty…. Will be a shame I plan to paint it :)

The cost was manageable at $47.00 however two exhaust manifolds will probably be $100 so for one-offs its OK however costs could get out of control.

So I think the inlet/exhaust manifolds and the oil gallery are very good candidates for 3D fabrication for the Howell V4.

Any creative exhaust designs are welcome as this will be the only other parts I get printed. I was thinking modeling the pipes of equal length like tuned extractors as the radius would be difficult to manufacture


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