Shapeways Cam for Mark VII

[shipwright]

Apparently I should not have left my 510 and my 500 in the shop without proper supervision because now I have a rusty little baby Mark VII on the way. I will be picking it up tomorrow and it is a “project” machine. The cam is intact (sort of) but has obviously broken in the past and been repaired with a little cleat and a couple of screws.
My question is can anyone give me a review of the plastic cam offered by Shapeways? I’ve seen it mentioned on several threads here that I’ve been pouring over but haven’t seen any reviews of how well one has stood up over any time. They also offer metal ones but at a much higher cost. Is it worth paying the bucks for metal or will a handful of plastic ones be more cost effective?

Thanks in advance. You will be hearing more about this project I’m sure.

[Mike]

I still have an original so I think it would depend on cost. I would go with metal if it’s cost effective.

[shipwright]

That’s kind of why I’m asking. The steel one is about 7x the plastic price and the aluminium one is about 10x.
Unless the plastic one is pretty useless it would seem to be the more cost effective. I’m just looking for someone who has that answer.

[JPG]

I think a plastic cam well cared for would be the most cost effective.

It is not like the cam is a 'consumable'.

Adequate lubrication is critical.

[shipwright]

Thanks JPG, that’s what I thought too. Then I talked to a friend with a printer and he’s going to make me one from the file that was posted on the Facebook group.
I’ll be taking advantage of your wonderful account of your restoration as I go. Thanks so much for the time and effort posting it.

[lahola1]

Here is a comment I made recently on another thread that had mentioned the 3D printed cams by shapeways.

"Engineering plastics were coming in big in the 60's. Even in car engines, (i.e. timing chain gears and other parts). The trouble is back then they didn't follow best molding practices. Meaning, the thicker the part, the colder the mold to shorten cycle molding times. Trouble is this molds stress and weakness in the plastic part. (plastic timing chain gears don't hold up well when occasionally drag racing your car or forgetting to lube the bearing on the speed adjusting sheave so the plastic cam melts).
As far as the 3D printed parts I would want to know the specs on the plastic they use. I have no idea what they mean by "versatile plastic" or "fine detail plastic". It shouldn't matter much on the rack but you need a high temp plastic for the cam. The temp on my cam follower has gotten to 150 deg F. I've seen PETG and ABS plastic mentioned in 3D printing. PETG should be good for a cam. I wouldn't use ABS.

Plastic works very well when the proper plastic is used and molded properly. For many years now they have plastic intake manifolds and top and bottom tanks on radiators in cars."

So I say again if the 3d printed cam is PETG It would probably hold up well if you keep the small bearing on the end of the speed adjusting sheave lubricated.

[shipwright]

Thanks, I’ve read that post.
I actually asked a friend who has a printer about what he thought of the “versatile plastic”. He said it was good stuff and should work fine. Then he offered to print me a couple for free from a filament called ASA that he thinks should work as well.
…… so I will get to try things out without the cost of international buying and shipping.
I will be posting about this rust to riches (I hope) project again so I will make a point of reporting my findings.