Critique my patterns, please

[Chucketn]

I'm building patterns for 3 tools I need/want. The tools are a follower/traveling rest and steady rest for my 7x lathe, and the body and banjo for the L.H. Sparey Dividing Head.
Please look at my patterns and offer any advise/criticism as appropriate. No draft has been applied yet to any of them. Do I need it? Do they need to be split?



Steady rest and Dividing Head shown in positin.






Thanks,

Chuck

 

[DAN_IN_MN]

I'm building patterns for 3 tools I need/want. The tools are a follower/traveling rest and steady rest for my 7x lathe, and the body and banjo for the L.H. Sparey Dividing Head.
Please look at my patterns and offer any advise/criticism as appropriate. No draft has been applied yet to any of them. Do I need it? Do they need to be split?

Pic's here: http://s571.photobucket.com/user/chucketn/library/patterns

Thanks,

Chuck

Your pics good sir!

I take it you're sand casting these? I would think that if you want to be able to remove the patterns from the packed sand you without destroying the impression left, you will want some draft.

[h=3]Draft allowance[edit source | editbeta][/h]When the pattern is to be removed from the sand mold, there is a possibility that any leading edges may break off, or get damaged in the process. To avoid this, a taper is provided on the pattern, so as to facilitate easy removal of the pattern from the mold, and hence reduce damage to edges. The taper angle provided is called the Draft angle. The value of the draft angle depends upon the complexity of the pattern, the type of molding (hand molding or machine molding), height of the surface, etc. Draft provided on the casting 1 to 3 degrees on external surface ( 5 to 8 internal castings)[SUP][6]

Taken from here: [/SUP]http://en.wikipedia.org/wiki/Pattern_(casting)

On your center rest, you might want to consider cam followers as a load point on your part.

 

[12bolts]

Chuck,
You will definately need draft on that sized patterns. Are you using commercial casting sand?
Due to the depth of the pattern for the dividing head I would be moulding that up as a split pattern. Otherwise that is going to need a pretty big flask. Are you making these from ally?
I cant see the travelling steady in any of the pics?

Cheers Phil

 

[Chucketn]

I do understand draft. The pictures are of exact mockups that will be turned into patterns or I'll make another pattern all together.
The parts will be sand cast. I will hopefully find someone close to help as I have not built my furnace or completed making my green sand yet. Of course, if I win the lottery...
The follower steady is not finished yet, so no picture.
In writing this reply, I realize I didn't allow for shrinkage, so new patterns will probably be made. I also have had several comments on the photos, so I'll be playing with that today, probably stage them on a piece of white chart board or maybe paint them a different color.

Chuck