practice materials

[Lakc]

If you have any srew machine shops in your area they make be able to sell you some short pieces.
Tin

Thats how I got my bridgeport, all the screw machine shops moved to China. :-\

 

[Tin Falcon]

I have been doing some research on machinable wax. Am considering making my own or at least casting the sizes I need from purchased wax or scraps thereof.
Machinable wax seems to be the cats meow for cnc learning and proving and even for making patterns for castings. It is recyclable at home. melt down the chips pour into an aluminum mold and an let cool overnight. You can use off the shelf electric kettle to melt it. And can even pour slabs in an off the shelf baking pan . another advantage is it cuts fast . One site i looked at recommends milling @100 ipm with a 1/2 " two flute cutter.
So the point here? If you want to cut or learn to cut machinable wax and learn in feeds and maybe even some threading on a lathe machinable wax is probably fine but it will not teach feeds and speeds for machining metal.
like mentioned before aluminum and 12L14 will teach a lot. Brass will cut easy with the right tooling. then try some drill rod. like said before make some parts. for real.
Tin

 

[Rayanth]

I had been more concerned with accuracy/movements than feeds and speeds, though I know I need to learn both. I think I will look at machinable wax for the accuracy training, and maybe even to make a part in practice before I make it again for real. Probably come in REALLY handy when I get around to the 28 cylinder

I do thank everyone for the input, it has given me much to think about, and I do love to think.

- Ryan

 

[shred]

I ran across a page on DIY machinable wax a while back, but I've completely forgotten where, so it might be worth trying to hunt up again.

 

[willburrrr2003]

I looked into machinable wax awhile back, from what I remember get cheap wax candles melt in pot...then start feeding in plastic (baggies, straws etc) the plastic ads stiffness to the wax, otherwise you can't machine it (it crumbles). you may have to play with it to get the mix right, but I have been told it is worth it. If you don't want to make it, you can buy it..then re-melt it down when done with it to start over.

Regards,

Will R. Everett, WA.

 

[pete]

Ryan,
For the most part I'd agree with all the comments mentioning using metal to practice on. You'll learn far more that way. But I think I can understand your thoughts too. Pine as mentioned is basically crap unless it it's real old growth and tight grained wood. Almost any hardwood is far better than any pine. While I haven't used or made machinable wax yet, That's a good idea too. Industry uses it for a lot more than training purposes as it's also used to prove out the planned machining steps. For a really complicated part, We as hobbyists can do the same. Until you have X amount of experience it's really easy, Especially on a mill to cut the part out from the raw metal plate or other metal shape too early and then it leaves you nothing left to hold the semi finished part for further machining steps. Preplanning your machining sequence of operations is your basic first step for any part. Scrap parts will at least teach you what not to do the next time. But that can get expensive for metal and even with free scrap material your cutting tool life and overall time. For something I've never done or as I said for really complicated parts I have and will in the future use a hardwood to help plan out that sequence of operations. The wood dust is a PITA but with a shop vac set up to collect the dust and chips while machining it's not too bad. You still need to somewhat protect the hard to get at areas with something like a plastic sheet and then super clean your machine tools at the end of the job even using a shop vac as the remaining wood dust that collects on the oiled surfaces can help to rust or gum up the equipment. Overall tho it's not too tough or time consuming to do.

A lot of pattern workers who make wooden patterns for casting metal parts use normall metal working machine tools to build really accurate patterns and I've yet to read anything specifically stating that wood shouldn't or can't be machined at least on manual machine tools. Depending on the size of your mill then an adapter to mount a router in place or along with the milling head would give you the spindle speeds required for machining wood. Carbide tipped router bits are a lot cheaper than the same shape designed for metal in a mill. Plus with a variable speed router set up those same router bits work well for aluminum and soft brass.

Try Googleing "Wagner safe-t-planner" It was originally designed as a rotary planner to be used in a drill press before the cheaper benchtop wood planners became comman. I use mine at the normal upper end milling speeds, For smaller wood parts it's unreal how well it works.It has 3 HSS cutting tips that are easily resharpened by the user. Planing wood to within a few thou is dead easy. For some cheap hardwood raw material then junk pallets used for shipping heavy items are almost always some type of hardwood. Cutoffs from a furniture manufacturing company probably could be had for free if there's one in your area. Wood glue is fast and easy so you can build up any size of blank needed. Maybe some of this will help you or somebody else out.

Pete