Author Topic: Cnc Spindle Speeder  (Read 2074 times)

Offline Brian.Garvey

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Cnc Spindle Speeder
« on: August 03, 2014, 11:45:47 PM »
So, second thread here....

I started life machining stuff with a router, then moved to a Bridgeport, then moved to a Hurco Knee cnc, then bought a Hurco VMC.

The above is for anyone that thinks I jumped straight to a cnc and wonder if I have a clue about 'real machining'  :thinking: :happyreader:

I still have the Hurco Knee cnc which I retrofitted and will probably never sell it.

As some of you may know this comes with a vari speed head as on the Kondias(spelling) and is limited to 4000rpm.

Since I do a lot of Aluminium machining I want to up this speed for driving the smaller cutters to enable me to give them some feed.

Enter the spindle speeder....its a simple thing really and a project I can handle(and complete :facepalm:) in a fairly short time frame.

It attaches to the quill, a pulley gets fitted to the nose threads, drives a belt, onto an idler, and another belt from there onto the high speed cassette which houses a Er16 Collet spindle.
The most costly part is the bearings within the cassette which Ill come to later - they are angular contact bearings at the nose, and a cylindrical roller at the tail.

The Cassette I have turned already, its made from En24 and threaded on the cnc, the race way slip fit cylindrical ground on the Matrix grinder.

Im locking the cassette into the main casting with a nut internally, I thought about threading it into the LM24 alloy casting but given that it may need to come out I thought a slip fit when heated and a nut might be a better option - more on that later anyhow...

Onto the main casting, the housing is cast in Lm24 as mentioned, Its a very simple casting and comprises of two mould halves and a core.

I chose(for once) to make the core box in the negative with wood and not in the positive as I normally do. This does away with striking two more negative core boxes off the positive core model in very expensive poly resin.

The main moulds I made up with some waste on the lathe, these are made in split form and mounted to a plywood parting plate(it only has to do one)....

The core box is cobbled together with more scrap - I normally cut patterns on the cnc but this time I did it all by hand(trained as a cabinetmaker) with the help of my new scrollsaw, FYI, the Scheppach scroll saws are ok for the money(170euro) but are no Hegners(or Wadkin Caliber!)

Here are the core boxes,

Zie saw,

Since I do a lot of production/batch/prototype castings I do all my casting with chemically bonded sand(sodium silicate) this allows one to leave them aside, and maybe sneeze and look sideways without them getting damaged. The patterns required are not as forgiving as with oil bond sand though, and one bad draft angle means jackhammer time....

Here is the drag with the core installed, Its also coated with Graphite/Zircon mould wash to give smoother finish. You can actually sand this mould wash too should you want a smoother finish - here I went with spray gun finish as its just a tool for mill....

The above is gated a bit terribly with no filter and a few other things but its fine for job in hand....

Here is the finished casting with the pattern match plate above it...


I then mounted it to mill for its virgin cut, a few things were milled here and the bore for cassette, bored...

I then turned it over locked it down and many cigarettes were smoked before hitting cycle start for the quill bore, and finish bore,

I cut a weird step in the top as the quill oil seal sits here on cnc and I dont want to wipe it out should I retract head too much by mistake....

The counterbore for cassette nut was cut also on the first jigging - did this with a large keyway cutter and a tangential lead move out before retracting the quill....

Thats pretty much all I have to report on the weekends progress so far....


« Last Edit: August 03, 2014, 11:49:23 PM by Brian.Garvey »
''Timing, perseverance and 10 years of trying will eventually make you look like an overnight success''

Offline stevehuckss396

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Re: Cnc Spindle Speeder
« Reply #1 on: August 04, 2014, 01:10:58 AM »
Nice work! Beautiful job on the casting
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Dave Otto

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Re: Cnc Spindle Speeder
« Reply #2 on: August 04, 2014, 01:34:58 AM »
Nice work and yes the casting looks great!

I also will be following along with this as I too have a CNC knee mill with a top speed of 5600 RPM