Some jobs just scream for a CNC mill

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David Morrow

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I probably wouldn't even be making engines if I didn't have a little CNC mill. And this is one job that definitely wouldn't be possible without it. This is a connecting rod for my Coss Horizontal Stirling - still in progress. The end mill in the photo is .020". I normally cut a .004" deep per pass at about .5" / minute. It may be able to go a bit faster & deeper but the whole job is only 8 minutes per pass so there's no need to rush. Total depth of the lettering is .010"




This is the project in full, or at least as far as last night's progress :
http://www.ldrider.ca/cnc/coss-horizontal/coss-horizontal.htm
 

Mike N

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Very impressive work! Are the prints still available? This looks like a good project for me!
 

sparky961

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David,

It looks like you've had a bit of experience at holding parts for CNC milling. This is perhaps THE most difficult thing for me to figure out sometimes. Think it'd be possible to post a few tips/tricks on doing this?

Thanks much!
-Sparky
 

Tin Falcon

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I see lots of bling . I am looking forward to getting my cnc going.
Tin
 

RonGinger

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I am currently working on a new CNC router. This will be a small, 14x14" machine. Its first job will be to engrave names in bricks for a fund raising project at the http://www.railwayvillage.org/ to restore the Merci Car.

This is an interesting project for me, as its the first time all my high tech tools (toys?) have come together. I bought Alibre CAD a year ago but never really took the time to learn to use it. For this project I was determined to do a full model before I cut a part. I posted a screen shot of it here in the Alibre topic a few days ago. Once I got over the basic learning hump it became very fast and easy to work out the parts and build assemblies.

After designing all the parts I had Alibre output DXF files for each part. I then ran Sheetcam on them to generate toolpaths and loaded them to my Jet knee mill. I have now cut all the parts and am about ready to start assembly.

The part cutting went great- most of them are flat plates with various drilled holes, cutout pockets and outline shapes. In all cases I clamped a sheet of 1/4" aluminum to the mill table and cut the part. It was a bit wasteful of stock since I had to have holding margins on all the edges. In the 'old days' I would have sawed the part outlines first then set up and added the holes. With CNC I cut all the holes first, then cut the outside edges.

Since this project has several parts that require 2 or 4 copies CNC has been great to cut the multiple parts. But I have also used it for every one-off part as well and Im sure its faster and more accurate.

Ill try to post a web page on this project, but it will be the central theme of my talk at NAMES in April "Adventures in Home Shop CNC"
 

kustomkb

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Your con rod looks great!

It looks like you've had a bit of experience at holding parts for CNC milling. This is perhaps THE most difficult thing for me to figure out sometimes. Think it'd be possible to post a few tips/tricks on doing this?
Here are pics of a nest made to hold a con-rod.





 

David Morrow

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Tin Falcon said:
I see lots of bling . I am looking forward to getting my cnc going.
Tin

It takes just a little more time to make something beautiful than it takes to make something ugly. I've tried to personalize it without loosing the original design. From what I've read, Terry Coss spent a lot of time making it a good runner and expected his students to add some custom touches. When it's all finished & running, I'm going to anodize some of it in order to add some colour and character. The remaining raw aluminum will likely be finely wet sanded but not polished; not entirely sure on that yet. Plenty of time for that.

Since it's my first, I've been extra careful. I've learned a lot of new techniques and more importantly, patience.
 

BobWarfield

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For a little help with CNC workholding, try Tom Lipton's new metalworking book. It showed up at our local Borders and has a lot of interesting tips.

Nice project here, I've bookmarked your web site as well!

I have that issue of the magazine and have held on to it because I loved the look of those "modified" Stirling engines. Makes a nice canvas from which to express a little creativity around the issue of "bling". CNC certainly helps that. I'm taking a break from my own CNC as we speak. Got it working so have finally started making my TB2 parts. It's all I can do to keep from "blinging" them.

Cheers,

BW
 

Jim E

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BW,
Do you happen to know the name of the book? I guess he has a couple of them out. Thanks

Jim
 

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