Rapid Technique: Preparing Plastic CNC Milling "Blanks" for Parts Used in Prototyping Scientific Equipment

Rapid Technique: Preparing Plastic CNC Milling "Blanks" for Parts Used inPrototyping Scientific Equipment

Richard H. Siderits MD

A. Maskey

Step 1: What is a Milling "Blank"?

When milling a part for a prototype piece of equipment, it is often useful to start with a piece of material that is not much bigger than the part that you are making.  This is called a Blank.  Using blanks, especially with Computer Numerical Control (CNC) systems, can reduce the amount of time needed to clear excess material during the milling process.

We describe a method for making plastic milling blanks for CNC milling operations and for making a "Jig" that helps place holes for conveniently mounting the blank onto the milling machine's table.

Comments

[rapidprototyping]

I found your chalkboar written instructable easier on the eyes to read. It is hence forwith declared all instyructables should be required to use said chalkboard fonts . I am serious we should adapt to change this is a definater improvement

[Culturedropout]

Wow.  That's a very attractive Instructable with a lot of good information.  Thanks.

[morphious69]

chips do waste in materials that are not reusable but anything polyethylene is all you need to reuse would be heat. it melts very easily  the only exception I have found for this is UHMW and to do that you need a controlled environment.

though that is not impossible either. I have scavenged both my vacuum cleaner (I hooked a shop vac up to collect dust from my mill) and the train tracks (they haul poly in big tankers as tiny pellets of various sizes and there are a couple poly container companies here so a ton of this stuff comes in for them to make 55 gal and other size barrels as well as underground containers like sewage and water retention for reuse (like to water lawns and other irrigation needs.) and the trains after being dumped always have a bunch in the small bent tubes that let it come out. usually those tankers are left open and one car will yield a whole grocery sack full of pellets of virgin unused polyethylene that can be heated with a heat gun into a mold or just on a flat surface. though you have to use silicon spray release agent on the mold or surface to get it off of the surface.) doing this on say a 1/8th inch thick aluminum plate though makes a great product for ridged plate with the poly being a slick bearing surface for any sort of roller activity.

[morphious69]

wow I am sorry to have to say but I am not seeing anywhere that all of this work could not replaced with a good set of layout tools and a decent cheap band saw. and I see plenty of places it could not be used that the band saw could.

like if I wanted to machine real world usable parts from delrin or UHMW polyethylene. both of which are far superior to your two part plastic and a lot cheaper if you just drop by a local plastics custom parts maker. *they have bins full of the smaller pieces that come off the 8 by 4 foot sheets they cut parts for customers out of. I buy delrin at about 3 dollars a square foot by quarter inch thick half foot by half inch and so on. same price for just about any polyethylene. and sheet acrylic for about 2 bucks or less per 2 square foot at 1/8th inch thick. both in clear and transparent colors(opaques are the same but I am using my lathe to make lenses for goggles out of it.)

PS&F is who I go through 918-622-8423 and if they will not ship let me know I will grab anything you get a quote online from them for and ship it for you. just pay the shipping to me to ship it priority mail to you.

you can find me at www.borgsteamfactory.com just use my contact page

and no I have no other affiliation to PS&F other than the lady who I deal with there is super nice and everyone else there has been extremely helpful.

[siderits]

Thanks very much for the info!

You are absolutely right. 

I just wanted to give people an introduction to the procedure with the most basic applications and example resources (especially for high impact material/resins). 

The great thing about Instructables is that people (like you) with experience can share both practical real world criticism and valuable insights.

When I use this procedure, its for blanks that have much more complex shapes.  I can just finish cut for detail  on the CNC platform.  It keeps me from wasting a ton of material that would be lost to chips.  

Of course, only now do I remember to mention that "part".

Thanks again for the info.

PS

Band saws rule.

[lemonie]

The slide format would work much better as a slideshow. To embellish the slides like this is to mix two different formats, it would look good as slides or an Instructable, but the hybrid is a bit odd. (This would apply to the rest also)

L