Using wood for practice?

[datosi81]

Hello all,
I have a little project I'm working on and I've already ruined a nice block of aluminum due to a mistake when drilling a long through hole. needed to drill thru 5" block of 6061, and I don't have that much drill length, so I tried to reposition and drill from the other end and meet in the middle, ended up about 1/16 off.

Is there any reason I can't use a block of wood to build a prototype of my project? Would my endmills cut the wood properly? Would the wood ruin my endmills in some way? I'd just like to be able to go thru the setup and machining with the wood and see that my setup will properly work before cutting up another 1.5"x3"x5" of 6061. :wall:

Thanks

 

[sssfox]

The end mill will work similar to a router bit, the edges may be a little rough due to the slower speeds involved.

If it were me, I would make a boring bar that I could mount between centers and drill a hole through the middle of it so I could put a tool bit in it. Depending on the size of the desired hole, either a 1/8" or 1/4" will do.
I use 1/8" round tools for most of what I do and hold it in place with a set screw. The boring bar has to be long enough to allow the bit to completely traverse the part, with a little extra.

Then, I would do my best to drill a hole all the way through, (a 1/16" offset isn't bad) slightly larger than the boring bar.

I would mount the piece of aluminum on the cross slide with the centerline of the hole concentric with the centerline of the lathe spindle. Once you get everything set up, lock the cross slide to keep it from moving.

Run the boring bar through it and adjust the bit for each pass until the final hole size is achieved.

It's easier to do than it is to describe.

Hope this helps,
Steve Fox

 

[Mainer]

Some kinds of wood are better than others. Mahogany, beech, and maple are pretty good. Some species, mostly exotic tropical hardwoods, are very abrasive and eat HSS cutters.

You might look into machinable wax. Google "machinable wax recipe" for information about making your own.

About the only downside to machining wood, assuming you don't have something that is abrasive, is the sawdust. It will absorb any oil it lands on and make a gooey mess.

 

[Philjoe5]

I don't know what size hole you're drilling but you can buy "aircraft" drill bits in 6" lengths for a few $USd:

http://www.wttool.com/index/page/category/category_id/14429/

Drilling small holes deeply requires lots of backing the bit out to clear the chips but otherwise is not tricky. You can practice on the aluminum chunk that's buggered.

Phil

 

[Dave Sohlstrom]

Machinable wax is your friend. It is not cheap but if you clean your machine well before you machine the wax and set up some temp guards to contain the chips you can remelt the chips and use it again.
It machines quite well and there is less chance of breaking end mills.

You can also get extra long drill bits 6" and longer.

Here is an example of a small part I needed to make 4 of in alu. The cutter was a 1/8" ball end mill turning at 4500 RPM 10 IPM feed rate.

Dave