Project M71

Please list it (for free) on https://www.lotusforsale.com

A great piece of Project M71 in place... http://www.projectm71.com/ProgressFrame.html

Looking good... So the table has all all bolt hole and stud hole diameters and centres corrected to the Lotus drawing, main body inner bore increased from 125.00 to 126.00 (marked as non-critical) and all the lug ribs marked with * are increased in size for strength... The radius smoothing to reduce stress is very good and we don't need the second ABS/VSS sensor (just one with a threas tapped), or the casting turret! With reference to the earlier point on the bearing mounting tappings, I don't see a 6.0 hole, just "Bearing recess bore step" at 5.00, as on the Lotus drawing but this is the step change on the large recess dia, I presume. So what dia are the bolt holes on the Lotus drawing and is this used?

How much thinner are they? I'll measure on my CAD and compare to my OEM parts Finite element analysis would be good to put some figures on stress/relative strength but billet material is a lot stronger than cast - here are the numbers for Tensile and shear strength for 6060-T6 and A350.0-T6 sand cast (what material is the OEM part cast in exac A356.0-T6 Sand Cast Tensile Strength, Yield >= 165 MPa @Strain 0.200 % >= 24000 psi @Strain 0.200 % Tensile Strength, Ultimate >= 234 MPa >= 34000 psi Shear Strength 143 MPa 20700 psi 6061-T6 Tensile Strength, Yield 276 MPa 40000 psi Tensile Strength, Ultimate 310 MPa 45000 psi Shear Strength 207 MPa 30000 psi

Good spot - my chart agrees Drill-and-tap-chart-MEFexport.com_.pdf

The billet parts will of course be stronger but this comment on social media is very relevant: Jonathan Edwards I'd look at the mode of failure and re-inforce that area (probably the lower link legs, that's where 2 of mine cracked). If you billet machine this you're paying for the part and the swarf, and the machine time so it makes sense to reduce as much as possible, plus a direct copy of a sand cast item isn't always ideal when you use different manufacturing methods.

Chis/Mike, Yes indeed, this is very good to see I am so glad to see this project come back to life - it was sorely needed and it's looking like the results will be excellent 😄

Ver 1.4 is the latest so far but this will need updating

For reference, here are quotes I had for pricing for 5 units for the ver 1.3 file and it's mirror, without tappings, in 6061, from xometry inbound1886336722.pdfinbound304828966.pdf

I've put the latest Novorota files here for safekeeping - and there's a link to the earlier Novorota files and all my CAD work http://www.projectm71.com/RearUprights.html?fbclid=IwAR2T-TiNfsgmAbDwvV4KGIeZ-a83C3X8wZBInqhSJe0ttG61WwIRR4O4S5A

Ignas has posted the ver 1.4 CAD files now and an excellent technical drawing, which some of the suppliers were asking for - these have the details on the tappings for the hub bolts. I have a look in CAD later and get a new quote

Just commented this on social media but I thought I would add here... Here is a Play List for those interested in the process to part machining, once CAD is complete... CAM (Computer Aided Manufacturing), tool selection & tool paths, NC/G Code (on which the Millling machines/lathes directly operate) and then the actual machining https://youtube.com/playlist?list=PL2UIEWwqJXrORlKXRQjQHY4ESaQNZdQi3 This process is all part of the setup costs that the estimates for the uprights include - and why costs reduce with greater part numbers, as the CAM only has to be done once

I'll let Mike comment/confirm, as I only concentrate on the Turbo Esprit and V8, but I don't see any changes in the model changes after the Commonisation of 'Eagle Chassis': May '89 Here: http://www.projectm71.com/changes.htm The ABS sensor holes are there in the CAD model and the webbing is as on the V8

Based in Bucks, near West London

Yes they should made in 6061-T6 - I'll ask for requote when Ignas posts the files but I guess people may have their favourite machining companies?