Laser cutting is the cheapest method but leaves some slag and hardens the steel
It may be difficult to tap the M6 treads due to the heat affected zone!
Send cut send can tap holes for you, but it adds ~$2/hole
water jet does not harden the material
Another way to avoid tapping the steel is to braze on M6 bosses. I can provide this CAD too, but I don’t want someone to accidentally download the wrong file!
Just keep in mind that Engin’s tool is designed for a 92mm bb shell with internal bearings. You can’t use that on a 74mm shell without modifications.
Confused by this analogy, even in street car applications various aero modifications can make a substantial grip improvement… sure there will always be people putting out there putting tacky non functional spoilers on their cars, but that doesn’t necessarily mean that all aftermarket aero is non functional.
Just because a bash guard doesn’t suit the riding that you do doesn’t mean its not still a widely used, functional component. Could be some internet sarcasm’s misunderstanding here.
I saw the internet sarcasm
Where I ride there are a lot of tree and rock over so I like having a bash guard. Plus it give you a .0000001 watt advantage.
One way to tackle the fixture dilemma would be to purchase and ISCG05 adapter, bolt it on the tab with spacers of the needed thickness to achieve the correct positioning along to the BB shell, put in in place with a BB cup, tack it on, take the picture and BB cup off, and finish the weld or braze.
At least hobby builder purposes, I can recommend just printing out a 100% scale drawing from CAD, and transferring hole locations with a centerpunch. There is in my experience plenty of tolerance for less than exact hole positions.
In that same mindset, here are some things I do that are different than OP. Mounting the cut pieces (I plasma mine) in a vice is challenging to avoid deforming, so I tend to just drill them clamped to the drill press table and tap with my hand held drill. I use 3/16 mild steel with less material “around the bb” and position them flush with the face of my BSA BB shell. Since any ground-hitting forces are primarily directly into the bottom two mounts, I place two ~1/2 stitch welds near them, and only a small weld around the end of the piece at the top.
Daniel, thank-you for sharing the ISCG mount resources, particularly the standard drawing! I hope to add an ISCG mount to a frame and may use the drawings.
Is anyone aware of a supplier for steel ISCG mounts or a source for waterjet cutting them (I can re-drill and tap the holes)?
