Idea For A DIY Spindle

Talk about all things CNC
Post Reply
unicornswag
Posts: 32
Joined: Thu Apr 03, 2014 1:51 pm

Idea For A DIY Spindle

Post by unicornswag » Fri Apr 04, 2014 7:51 pm

So here's my idea for a cheap DIY spindle that I plan to build for my homemade CNC mill. It will mainly be used for pcb's, and light engraving of wood. All parts can be found at my local hardware store. Instead of spending extra to order a precision machine steel shaft, It'll just use regular 1/4" rod epoxied to two cheap roller bearings which are encased in a stack of MDF blocks. Any suggestions for improvement before I get to work on it?
Attachments
spindle.png
spindle.png (184.3 KiB) Viewed 1993 times

edwardrford
Posts: 1250
Joined: Mon Apr 09, 2012 5:40 pm
Location: Dixon, IL
Contact:

Re: Idea For A DIY Spindle

Post by edwardrford » Fri Apr 04, 2014 8:05 pm

Looks a lot like the one from MIT designed for a DIY cnc.

I couldn't find v1 of their spindle but it used mdf as stacking (like yours) and a vinyl tube as a flexible coupler.

Here's a sketch of v2:
spindledrawing.jpg
spindledrawing.jpg (67.35 KiB) Viewed 1988 times
I've always wanted to try the approach, but every time I do the BOM, it ends up cost about as much as a generic rotary..

With that said, it may be quieter!

-Edward
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

unicornswag
Posts: 32
Joined: Thu Apr 03, 2014 1:51 pm

Re: Idea For A DIY Spindle

Post by unicornswag » Fri Apr 04, 2014 8:12 pm

So what does V2 use instead of the stacked MDF? It's hard to say based on that sketch, since the entire outer shell is labeled "Bronze Bushing", but that doesn't seem right.

cvoinescu
Posts: 4442
Joined: Thu Jul 19, 2012 6:50 pm
Location: Camberley, UK
Contact:

Re: Idea For A DIY Spindle

Post by cvoinescu » Fri Apr 04, 2014 8:15 pm

I think everything is fine for very light duty, up to the set screw coupling. That's likely to add a lot of runout. "Proper" spindles have the collet seat machined directly into the shaft, which ensures they're concentric (and stay that way). I don't know of an easy way to DIY that (except if you have access to a lathe).

Wouldn't a cheap Chinese DC spindle be better?

Edit (after Edward's post): drilling out the center of the rod is likely to decrease runout due to the coupler. I guess you can use the spindle itself and a fixed chuck with a drill bit as a sort of lathe, to ensure the hole is centered. Still, the cheap Chinese spindle is pretty much the same thing, but ready-made and with a much better collet.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

unicornswag
Posts: 32
Joined: Thu Apr 03, 2014 1:51 pm

Re: Idea For A DIY Spindle

Post by unicornswag » Fri Apr 04, 2014 8:15 pm

Oh, Okay, I looked up the part number and a large bronze bushing is exactly what that is. I wonder why that was necessary over something cheaper lice a piece of PVC pipe? Maybe it was just the right size?

WillAdams
Posts: 8514
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15
Contact:

Re: Idea For A DIY Spindle

Post by WillAdams » Fri Apr 04, 2014 8:17 pm

We do have two links on this on the wiki (one of which is to the M.I.T. plan Edward mentioned, I believe):

** [http://mtm.cba.mit.edu/toolheads/spindle/makeit.html plans on MIT to make a spindle]
** http://opensourceecology.org/wiki/CNC_C ... ll_Spindle
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

edwardrford
Posts: 1250
Joined: Mon Apr 09, 2012 5:40 pm
Location: Dixon, IL
Contact:

Re: Idea For A DIY Spindle

Post by edwardrford » Fri Apr 04, 2014 8:21 pm

I'm not sure what they used. I never saw one mounted on a machine. The MDF used in v1 was both a stack (to separate/space out the components) and used to hold the bearings in place.
Here's a pic i just found of it in use:
spindle.jpg
spindle.jpg (7.59 KiB) Viewed 1981 times

My best guess (something I've failed at miserably many time before): I would say the bronze bushing gives it enough rigidity that one could to it. Maybe in the same fashion that we clamp to the dw660: with a hole and slot with a bolt.

Again, i'm just guessing on that one. As a point of reference, it's the same general idea (hard outer shaft with bearings in it) that both cnconabudget and the wolfgang spindle employ.

-Edward
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

WillAdams
Posts: 8514
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15
Contact:

Re: Idea For A DIY Spindle

Post by WillAdams » Fri Apr 04, 2014 8:29 pm

Your note about cost was an interesting point.

Would it be worthwhile to purchase some commercial tool w/ an electric motor and then disassemble the housing and craft a new one using the ShapeOko?

What would be a suitable material?
Is there some commercial off-the-shelf item (such as the bronze bushing) which could be so re-purposed?

I keep going back to the reviews of the DW660 noting that it has its bearing encased in plastic...

I'm really bummed that we weren't able to upgrade the spindle for the ShapeOko 2 --- I've been quite happy w/ my Harbor Freight 1/4" Trim Router thus far and have wondered if the equivalent Altocraft unit was considered?
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

cvoinescu
Posts: 4442
Joined: Thu Jul 19, 2012 6:50 pm
Location: Camberley, UK
Contact:

Re: Idea For A DIY Spindle

Post by cvoinescu » Fri Apr 04, 2014 8:37 pm

unicornswag wrote:Oh, Okay, I looked up the part number and a large bronze bushing is exactly what that is. I wonder why that was necessary over something cheaper lice a piece of PVC pipe? Maybe it was just the right size?
It needs to be rigid -- both the inner and outer races of the bearings must be rigidly connected to each other, or the spindle won't be able to withstand lateral loads without flexing every which way. And PVC would probably soften as the bearings heat up, too.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

edwardrford
Posts: 1250
Joined: Mon Apr 09, 2012 5:40 pm
Location: Dixon, IL
Contact:

Re: Idea For A DIY Spindle

Post by edwardrford » Fri Apr 04, 2014 9:05 pm

WillAdams wrote:Your note about cost was an interesting point.

Would it be worthwhile to purchase some commercial tool w/ an electric motor and then disassemble the housing and craft a new one using the ShapeOko?
While it wouldn't be practical to purchase a tool and dismantle it for reuse, I have always thought it would be practical to build a spindle around the standard ER11 shank/collet sold on ebay for around $10.
er11.png
er11.png (114.93 KiB) Viewed 1965 times
In theory all one needs are: a rigid outter casing (like the bronze bushing), 2 bearings (probably angular contact), and a source to turn the shank.

In reality, it's a lot harder than that because you need a way to capture bearings, a way to capture the shank (there are no threads), you need to somehow preload the bearings, you need a method to both stand off (be it to the side or above) the motor, you need a method to connect the motor to the shank (be in belt/pulleys, or direct). On top of that everything has to be super tight, so when it's spinning several thousand RPMs, it doesn't vibrate itself apart...

There are many people who have done something like this with either RC motors (bart's comes to mind).
bd_rc_spindle.jpg
bd_rc_spindle.jpg (16.49 KiB) Viewed 1965 times
One of my favorites is here:
diy brushless spindle 10.JPG
diy brushless spindle 10.JPG (54.83 KiB) Viewed 1965 times
I have yet to see one that is straight forward and requires no 'skillz' to assemble.
... if the equivalent Altocraft unit was considered?
Bang for buck wise, to date, the standard rotary tool is the best choice for an included spindle. it's capable enough to let anyone get started, and it costs little enough that discarding* (either if it breaks or for an upgrade) doesn't make you feel terribly wasteful.

Since about 2009 I've been looking for a DIY spindle solution. It might be fun for us all to come up with a design and see what we can do.

-Edward

*not necessarily throwing away, more than likely just putting in your toolbox
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

Post Reply