A new respect for aluminum

creasman

Jim
Staff member
Corporate Member
Earlier this year I purchased a used Delta drill press. After I got it home I found that the set ring which holds the depth stop was cracked. The original part is cast iron and subject to break if it is over tightened. It's an older model Delta and I was not able to find a replacement part. It's not a complicated part and I decided to make one.

My first attempt was out of solid surface counter top (e.g., Corian). I've used that for a lot of things. It's a super hard plastic that is almost indestructible -- almost. In this case it cracked when I tightened the bolts to get a snug fit.

Next up for replacement material was aluminum. I ordered a 3/4" thick bar (same thickness as the original part) and set to work. This is where my new respect for this material was gained. I've worked thinner aluminum stock using regular wood-working materials. One of the challenges of working aluminum is that it clogs up your tools. It simply fuses into spaces -- like the gullet between the teeth of saw blades and files. You have to clean these frequently.

I tried a variety of approaches. Using a hole saw produced a high-pitched noise in the range that causes my wife to leave the state, and didn't really cut. A sabre saw with bi-metal blade was also no good. It cut better, but was horribly slow and I spent more time keeping the teeth clear than in use. Did I mention this aluminum was 3/4" thick?

What finally worked was a combination of drill, hacksaw, router and elbow grease. I drilled out most of the hole and then used a hacksaw to remove material as close to the final shape as I could. Using double-sided tape to hold a template in place I removed the rest with a flush-trim router bit in multiple passes, about 1/8" at a time. It took most of the afternoon to get to the final part (Did I mention the aluminum was 3/4" thick?).

I smoothed all the edges using spindle and orbital sanders. Along the way I drilled and tapped the holes. I'm pleased with the final results -- better than the original part in some ways.

IMG_3461.JPG

New and old part along with aluminum bar from which it all began.

IMG_3462.JPG

Part installed and ready to use.

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One very messy shop floor. Those are flakes of aluminum.
 

AllanD

Allan
Corporate Member
Great job! I'm impressed. On a similar note, that L shaped piece that the big nut hits against tended to bend on my Delta. I solved that by welding a triangular piece at the bend.
 

Mike Davis

Mike
Corporate Member
Hard work…
I made aluminum letters for a big stone entrance sign way back in my 20s.
It was 1/2 inch thick. I used a skip tooth blade on an old Sears bandsaw
then sanded with a 1 inch belt sander.
Each letter took a day. The letters were 16 inches tall.

$5000 was way too cheap for that job, but I learned a lot.

Took the bandsaw to metal recycling when finished.
 

tvrgeek

Scott
Corporate Member
Very nice. Original was clearly a bad design and probablly poor casting. I might have used Delrin, but that is me.
I wish my Delta had the speed-nut rod depth rather than the wheel on the right side.
 

Oka

Casey
Corporate Member
Nice Job ! You could is so motivated anodize the part. It is pretty way to do.
I try whenever possible never to do the mass cutting in the shop because of the metal flakes get everywhere
 

creasman

Jim
Staff member
Corporate Member
On a similar note, that L shaped piece that the big nut hits against tended to bend on my Delta. I solved that by welding a triangular piece at the bend.
Good to know. The give in that piece bothers me a bit a well. I don't think it's enough to be a problem, but something I may address.
 

Oka

Casey
Corporate Member
In the future for things that need to resist shear stress might look at 7075 aluminum, way stronger, less common though. However, it does not take to welding at all.
Good to know. The give in that piece bothers me a bit a well. I don't think it's enough to be a problem, but something I may address.
 

creasman

Jim
Staff member
Corporate Member
The part in question is a steel bracket. @AllanD's solution of reinforcing this with another weld is a good fix. I doubt I'll do anything further, though. It takes significant force to flex it and then it's hardly noticeable.
 

Dee2

Board of Directors, Vice President
Gene
Staff member
Corporate Member
Sounds like a contest submission in the making.
 

drw

Donn
Corporate Member
Jim, I know next to nothing about working with metal, but I can recognize quality work when I see it and I see both quality as well as functionality. This is especially impressive since you are not really setup to work with heavy gauge metal...well done!
 

JNCarr

Joe
Corporate Member
Jim - as always, some excellent metal work. For future reference you might consider Sendcutsend.com which I use on a very regular basis. They laser and waterjet. Very accurate (certainly not machined accuracy, but very good). They dont do 3/4" thick, but for thick parts I have epoxied multiple thinner layers together with great success. I didnt include index pin holes in the drawings, but that's how I usually align a stack up.

As a cost example, I sent them a mockup of your part shown below (obviously, you'd still need to cut the main ring open and drill and tap). For 2 layers of Micarta it would be 34.20 delivered. For 3 layers of 5052 Al it would be 29.00 delivered (actually was less, but they have a 29 minimum order). Usually takes about 7-10 days from the time you submit the CAD drawing to have it in hand.
 

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