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Tool Post Milling/Drilling Attachment

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Roderick Jenkins14/03/2019 14:36:01
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1670 forum posts
423 photos

Being the impatient soul that I am, I have conceived the need for an easily mountable tool that can be used for milling and drilling items held in the lathe headstock. I do this quite a lot with a vertical slide and 95% of the work is done at centre height. This is my attempt at a tool post mounted attachment:

tm2.jpg

tm1.jpg

 

tm3.jpg

 

tm4.jpg

The spindle is based around a pair of angular contact bearings and an ER11 straight shank spindle, both from ARC. The motor is a 200W 230V treadmill unit with speed control from ebay **LINK**

I'm waiting for a pulley cover to print at the moment.

Cheers,

Rod

Edit:  I paid £44 for the motor  -  looks like he might be out of stock with speed controllers for the moment.

Edited By Roderick Jenkins on 14/03/2019 14:40:30

John Rudd14/03/2019 19:41:46
1355 forum posts
58 photos

Roderick,

Is the motor a universal type or permanent magnet? ( guess I really ought to ask the seller....)

Edited By John Rudd on 14/03/2019 19:42:23

Roderick Jenkins14/03/2019 23:01:52
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1670 forum posts
423 photos

Good question. This looks like the speed controller **LINK** It seems to run equally well in either direction by swapping the motor leads.

Nicholas Wheeler 116/03/2019 16:23:09
211 forum posts
11 photos

I couldn't see the point of making a spindle driven by a separate motor, and didn't have any the bits to do so.

So £90 later, which included a set of ER11 collets and power supply, plus about an hour's worth of work, most of which was adapting the mini-lathe vertical slide to my WM250:

millingmotor2[1].jpg

and

millingmotor[1].jpg

so it's height adjustable, and both the cross slide and vertical slide can be adjusted for all sorts of compound angles.

Clive Foster16/03/2019 19:33:47
1596 forum posts
45 photos

Thats a very neat job Nicholas.

Usual reason for going the separate motor and spindle with belt drive route is to be sure the bearings are able to handle cutting loads. In particular most smaller size motors have bearing arrangements with fairly limited thrust load capability.

Think I'd look into using external thrust bearing to carry the loads.

Clive.

Roderick Jenkins16/03/2019 19:47:55
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1670 forum posts
423 photos

I'd considered a spindle like the one Nicholas used. My concern was that there might be insufficient torque to drive a 6mm drill through steel at 1000 or so rpm which is at the bottom end of the speed range for a 12000rpm spindle. I, too, had doubts about the robustness of the bearings. Hence my clumsy looking but workable solution. Happy to be proven wrong smiley

Rod

Nicholas Wheeler 116/03/2019 21:18:42
211 forum posts
11 photos
Posted by Clive Foster on 16/03/2019 19:33:47:

Thats a very neat job Nicholas.

Usual reason for going the separate motor and spindle with belt drive route is to be sure the bearings are able to handle cutting loads. In particular most smaller size motors have bearing arrangements with fairly limited thrust load capability.

Think I'd look into using external thrust bearing to carry the loads.

The photos flatter it, it's not the prettiest thing when you see it in the metal. But by tapping 8 holes in something I already had, it gives a lot of adjustments over a large range of movements which should make it usable for the clock wheels I've not started for the last 3 years......

I've recently found a chunk of aluminium that would make another bracket for attaching to a QCTP tool holder. That would allow for the quick deployment of it for things like fluting knobs or crossdrilling. It's this sort of job that makes me wish I had bought a wedge type post, as integral Dixon holders are not something I want to make.

Robert Atkinson 216/03/2019 22:53:26
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135 forum posts
12 photos
Posted by Roderick Jenkins on 14/03/2019 23:01:52:

Good question. This looks like the speed controller **LINK** It seems to run equally well in either direction by swapping the motor leads.

As it reverses by swapping the supply it is 99% certainly a permanent magnet DC motor. It looks like a PM. The odd 1% are the same as a "universal" (AC/DC) motor that has a full wave rectifier connected to either the field OR the armature winding. I've seen this on a couple of motors, it allows you to have a remote reverse switch with only two wires to the motor. It can be retrofitted to a standard universal motor. As you probably kinow to reverse a universal you have to swap just the field or armature.

Robert G8RPI.

Edited By Robert Atkinson 2 on 16/03/2019 22:54:31

Roderick Jenkins16/03/2019 23:23:21
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1670 forum posts
423 photos
Posted by Robert Atkinson 2 on 16/03/2019 22:53:26:
Posted by Roderick Jenkins on 14/03/2019 23:01:52:

Good question. This looks like the speed controller **LINK** It seems to run equally well in either direction by swapping the motor leads.

... As you probably kinow to reverse a universal you have to swap just the field or armature.

That's a very bold assumption frown Thanks for the information yes

Rod

Ian S C17/03/2019 08:32:17
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7220 forum posts
227 photos

Most tread mill motors are PM DC motors, they also make quite good alternators.

Ian S C

Robert Atkinson 218/03/2019 07:36:24
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135 forum posts
12 photos
Posted by Ian S C on 17/03/2019 08:32:17:

Most tread mill motors are PM DC motors, they also make quite good alternators.

Ian S C

A PM DC motor will never make an alternator of any kind. The commutator rectifies the rotor output so they produce DC. They don't even make good generators as you cannot control the output voltage for speed or load variations. I guess you could use a 230V one with a switchmode step down voltage regulator but its a bit of a weird approach.

Robert G8RPI.

AdrianR18/03/2019 14:59:50
49 forum posts

I was looking through MEW back issues and saw in #52 and #53 there is a description how to build the Quick Step tool post milling attachment. Might give you a hew ideas.

lfoggy19/03/2019 11:49:18
31 forum posts
5 photos

Nice job Roderick.

I am in the process of building a similar device based on an Arrand milling/drilling spindle. I just need to acquire a motor and was debating what to use. I was thinking of a 100 or 150w permanent magnet DC motor. I am not anticipating drilling more than around 4mm holes in steel or using small (>4mm) slot drills. Your 200w motor looks quite big but I guess you chose this because you are planning to drill bigger holes.

Have you found 200w to be OK for your application?

Hollowpoint19/03/2019 14:26:06
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120 forum posts
8 photos

Roderick

Ive been looking at that motor for a small wood turning lathe do you think it would have sufficient power? Also does it have holes for face mounting?

Roderick Jenkins19/03/2019 16:25:11
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1670 forum posts
423 photos

Guys,

I have successfully used a 120 Watt sewing machine motor with an Arrand spindle. 6mm drills are a bit of a struggle but it will drill 4mm with ease and drives a 6mm endmill OK providing the depth of cut is not too big. I was guided in my choice for the new system by the capacity of the ER11 collet chuck.

cc2.jpg

I couldn't really comment on use for a woodturning lathe, it depends on so much. For guidance, the top speed of the treadmill motor is 4000rpm so I would probably at least halve that speed with the pulleys for wood turning but, again, it depends...

HTH,

Rod

geoff walker 119/03/2019 16:43:53
274 forum posts
116 photos

Hi Rod,

Nice set up that, I like what you have done.

You and Nick have also got me thinking. I have used this set up for years on my M type but now I have the seig mill I never use it.

With not too much trouble I guess I could retain the V/S, turn the potts through 90 degrees and mount the parvalux over the top.

We shall see, thanks to both for posting your work, very interesting.

20180905_143510.jpg

Geoff

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