Author Topic: Holt 75 from Germany  (Read 3633 times)

Offline michelko

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Re: Holt 75 from Germany
« Reply #15 on: January 10, 2021, 11:43:46 AM »
Hello Michel

I have just watched the video - I knew how it's done, but this is the first time I really could see how well and cleanly the cutter removed the material - thank you  :ThumbsUp:

I guess that this is a homemade tool, so did you use any tricks to set the depth of the cut ?  And how accurate could you set it for the diameter you aimed for ?

Per
Hi Per,
the bar is an ground drillrod. i just meassured the hight of the cutter bit above the rod. So for example to bore a 14mm hole i set the cutter tip to 2mm above the rod surface.
I still have to measure the achived diameter but in the end it is not critical because of the bronce inserts. i will fabricate them to meet the bored hole.

Regards Michael

Offline michelko

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Re: Holt 75 from Germany
« Reply #16 on: January 17, 2021, 12:28:13 PM »
Hi Guys,
worked a little on the cams. I made them from Drillrod and they will be hardened also the followers.
I mainly used the profile like in George Brittnells plans but instead of a tangent between base and nose i used a radius.
So the  follower will not do abrupt movement.
The bar was setup in my rotary table (not used as this just as holder) and milled with the cnc function of my bf20.
The cams came out nice and just needed a little sanding/polishing.
The cams has a little noth of 2 mm, these is used to index the cams on the shaft. The cams will be fitted with loctite to the shaft, the pins will also be an additional security against loosing /rotating of the cams.
The shaft will be an anharded drillrod of 6mm like i similar used in the bugatti.

Offline michelko

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Re: Holt 75 from Germany
« Reply #17 on: January 17, 2021, 12:31:29 PM »
here is a short vido from milling

<a href="https://www.youtube.com/watch?v=dfswU4RaAdI" target="_blank">http://www.youtube.com/watch?v=dfswU4RaAdI</a>
« Last Edit: January 17, 2021, 12:42:10 PM by michelko »

Offline michelko

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Re: Holt 75 from Germany
« Reply #18 on: January 17, 2021, 12:37:48 PM »
Here is a drawing with the meassures of the cams

Online Vixen

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Re: Holt 75 from Germany
« Reply #19 on: January 17, 2021, 02:38:25 PM »
Hello Michel

I believe we all have a problem with videos no longer showing.

Nice work on the Holt engine

Mike :ThumbsUp:

« Last Edit: February 01, 2021, 06:20:26 PM by Vixen »
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline michelko

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Re: Holt 75 from Germany
« Reply #20 on: February 01, 2021, 12:10:20 PM »
Hi Guys,
here is a little update on the cams and the shaft.
With the indexing table i drilled the holes into the shaft . The little pins are indexing the cams and also give a little safety against loosing. The cams are loctited io the shaft after hardening.
The cams are made from drillrod, heated to 800 ░C and quenched in oil. Then annealed at 290░c for 1,5 hours.
Also turned the outer bearing and did a testfit with the shaft.
Just have to make the split middle bearing.


Offline michelko

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Re: Holt 75 from Germany
« Reply #21 on: March 16, 2021, 03:34:22 PM »
Hi,
here is a little update on the holt.
I made the cylider jakets. They are turned from some free turning steel. For this i used my temporarely to cnc converted lathe.
I also fabricated the big gear for the cam shaft.
Unfortunately i had some problems to make the hole to spec. i aimed for 6 H7 but something went wrong while reaming.
At the end i bored it out on the lathe to fit the camshaft.

Regards Michael

Offline gbritnell

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Re: Holt 75 from Germany
« Reply #22 on: March 16, 2021, 03:50:45 PM »
The engine is coming along great! Thanks for the videos on your progress. That was the main reason I split the crankcase so it would be easier to machine the main bearings.
gbritnell
Talent unshared is talent wasted.

Offline michelko

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Re: Holt 75 from Germany
« Reply #23 on: January 10, 2022, 10:25:21 AM »
Hi guys,
long time no post.
Yesterday i found some time to work on the rockers.
Made them from freeturning steel.


Regards Michael

Offline gbritnell

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Re: Holt 75 from Germany
« Reply #24 on: January 10, 2022, 01:09:31 PM »
I'm glad to see you are getting back to your Holt build.
Talent unshared is talent wasted.

Offline michelko

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Re: Holt 75 from Germany
« Reply #25 on: January 10, 2022, 03:24:32 PM »
Hi George,
yes i am too. But in the meantime i had another toy to play with that took my whole focus.

Greetings
Michael

Offline michelko

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Re: Holt 75 from Germany
« Reply #26 on: May 30, 2022, 08:30:39 AM »
Hi guys at least i found some time and inspiration to work on the holt again.
I started on the crankshaft. I decided to build it up from pieces.
The main shaft is from 12mm drill rod an the rod shaft s are from 10mm drillrod.
The webs where milled and drilled/reamed from c45 Steel.
All pieces will be glued together with loctite and additional pinned.

I made some good experiences on my bugatti build with the loctited crank so i am hoping this will also work for the holt.

Michael

Offline michelko

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Re: Holt 75 from Germany
« Reply #27 on: May 30, 2022, 08:33:56 AM »
Here is ashort Video from milling the webs with my BF20 CNC


Offline Admiral_dk

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Re: Holt 75 from Germany
« Reply #28 on: May 30, 2022, 11:36:02 AM »
Distractions - yeah there can be many of those  ;)  great to see you back here  :cheers:

Per

Offline michelko

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Re: Holt 75 from Germany
« Reply #29 on: June 14, 2022, 02:36:07 PM »
Here is my setup for gluing the crank.
Later i will additionaly pin it. Just to be sure the connection  won┤t come loose.