DIY CNC Camgrinder

marsheng wrote: Thanks rodw

I've looked up external offsets but I'm non the wiser.

What would the G-Code look like ?

I'm no expert on lathes but I think you would program a simple turning operation and allow the external offset change the X axis coordinates to follow the cam lobe profile. eg at TDC of the lobe, you would be the height of the lobe away from the main shaft circle and back on it when the lobe ends due to some algorithm that accepts the rotary position as an input.

I'm not sure but there is a new hal-port pin type in master that may let you feed some external point data into a component.

You should look at the external offset sims in V 2.8 and 2.9

I did a search on Cast iron and epoxy granite and it does stack up very well.

See here

Epoxy Granite

Here is a great one

Epoxy Granite 2

Mnn Now I'm getting excited to get started

marsheng wrote:
Mnn Now I'm getting excited to get started

I can't wait to see that billy kart with a great big lumpy cam!

If all goes well it will be for a 1964 Ducati MK3 250.

My starting point,

schmidtmotorworks said: The data is 6 decimal, I doubt the measurements are 6 unless in a controlled temperature environment with exceptionally accurate tools. .

I have a different approach to the Performance Trends unit. I let my shaft run through 10 + revolutions then average the data. This gives good results. Even still I can massage the data to make sure it is clean. That is why I'm looking at point to point on my grinder as that is what the original data is. My end result is to measure the valve movement and not that cam. That is what I want to be correct. Changing valve length, seat height etc all affect motion when you have rockers.

The duplicate measurement method will get you by, but if you round to less than 0.0001" the acceleration curve will not be smooth as much of the acceleration values are in that range. The G-code (in inches) needs to be 5 places past decimal.

On a master at 0.0001" and 0.1 degree steps, the faceting is noticeable and needs to be polished out. The grinder even sounds smoother when you do.