The Home Machinist!

This may not be the right forum section for this question but I'll ask it here anyway.

Since I am preparing to make a riser block for my milling machine I've been reading up on it and some say cast iron is better as it doesn't flex like steel will. I have a foundry near me so it might be something I can do (make the mold for them from wood) and have it cast, then machine it to final dimension. The size will end up being 12" dia x 5"h x 1" wall thickness.

Is this worth it and would it be better than machining it from plain steel?

Thanks in advance.

Cast iron is better for such things but I've not found that the difference is all that great. The major advantage is said to be vibration damping.

A custom casting is certainly the ideal solution, but won't be rather pricey? Can you buy a suitable piece of scrap from them?

A coin toss? Cast might be better but will certainly take longer. I have had no issues with the steel riser I made. Might be worth a visit to the foundry, and as you suggest, might have a suitable lump. Probably will take a pattern and a core box as you probably need a core through the middle, less shrinkage and no sense paying for the extra iron.

Since your riser will only be 5" high, steel should work just fine. Not so much material to flex.
If it was 12" tall, then the vibration damping of cast iron could help.
Go with steel pipe.
~RN

Cast Iron has 10 times the vibration killing ability over steel. You never see a cast iron tuning fork !
Aside from that and it possibly being cheaper, Steel is fine as you load the riser under compression and the sandwhich parts are Cast Iron .
We made a couple of risers at work , like 5 and 8 inches for some special jobs.
We bought steel tubing with 1 inch wall thickness ,cut it to size and had it stress relived , then Blanchard ground and painted the outside .
Worked great.
Rich

PS
If you make your own longer screws, use "Stress Proof steel ( LaSalle Steel) for stock
Easy to cut and hold beautifully.
Rich

Thanks for the thoughts guys!. Maybe I'll post some pics of the final outcome. Judging by the comments either will work for the size I need. I'm leaning toward cast but cost will dictate the outcome.

What mill do you have?