Wheel holding arbor.

[raynerd]

I am looking to make a wheel holding arbor to hold clock wheels for truing and eventually cutting. I want to mount the wheels directly in my RT in the 2MT. Since many wheel blanks have different centres, but these need cutting to size before truing, it would be expensive and time consuming to make a new arbor for each wheel centre hole with a 2MT. I have been looking online and I have found a few descriptions but nothing explicitly clear. This is my current design and understanding. sorry nothing fancy, just a bit of "paint"ing!



I will need to cut different centre collets / bushings (I don`t know exactly what they mean by a collet in horology but this is my understanding) for each wheel, the collet narrows the centre bore to match the arbour diameter. The hole lot is bolted to the sacrificial back plate. I have even seen people use wood as their back plate.

I was thinking about having a M4 bolt and consequently 4mm diameter arbor, this would allow me to mount any wheel with the smallest centre hole of 4mm, anything bigger and collets can be used to mount it.

Anyone any thoughts about this? Can anyone see any problems or a better way of doing it?

Chris

[raynerd]

Just been thinking, perhaps it would be easier to drill and thread a hole in the arbour and bolt the hole lot on? Can`t see it making a big difference but perhaps a little easier to tap a hole.

Also, just been searching online and I have found this nice idea of turning in a box to allow you to accurately bore out a centre hole further. Would you still need to use collets with this method or could you just drill for the mandrel/arbor diameter and then bore then to size after? Just a thought:





Chris

[sbwhart]

Chris what you have to concider is the level of acuracy you want, with this design of arbour your incesing the oportunities for any error to build up, ie with one register diameter you'll have a slight error in fit, with two register diameters you have two slight errors in with three etc etc, added them together = bigger overall error.

Thats why its better to tranfer the job in the lathe chuck over to the RT if you've got a good adaptor for your RT, it reduces the number of errors your adding together.

Hope this helps

Stew

[raynerd]

Hi Stew,

Thanks for your reply, my plan was to turn the wheel in the 3MT (using a 2-3Mt sleeve) in my headstock on the lathe - that being said, I`d not considered how I`ll stake the MT into my lathe headstock as I haven`t a draw bar long enough, guess I`d need to make one. I`d then take this out of the headstock, remove the sleeve and then transfer to the 2MT RT. Will this still add the errors and best to use a chuck and adaptor? - if you think that mounting in the chuck will be better than I`ll knock this idea on the head.

Chris

p.s - know anything about module "size" gear cutters?

 

[sbwhart]

Chris I've sent info on modular size gears to your email adress, can't seem to get into photo bucket this morning for me to add it her.

Regards mandrell you've just got to come up with the best option for the kit you've got, try and keep the oportunity for errors to the minimum.

Stew

[NickG]

Chris,

Would a stepped arbor be better with steps for the ranges of sizes you need. Then you will need some different bushes made up to enable the nut on the front to clamp, but at least this way you only have 1 source of error, the fit between which ever step and the disc as Stew said. Also, what is the range of hole diameters? If you use your method below, wouldn't some of the collets be extremely thin in section?

Nick

[raynerd]

Hi Nick

I have since changed from this design a little Nick but in princible I`ll be using something similar to a steped arbor. I`ll post it up when I next use it again and thanks for the comments.

Chris

[bogstandard]

If you end up wanting to do this sort of thing a lot, maybe you could invest in a set of these.

http://www.arceurotrade.co.uk/Catalogue/Expanding-Mandrels

I use the Straight Shank Expanding Mandrels (Quick Release) ones.

Or if you have slitting saw facilities, you can easily make up your own like these.

http://www.chronos.ltd.uk/cgi-local/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2echronos%2eltd%2euk%2facatalog%2findex%2ehtml%3fhttp%253A%2f%2fwww%2echronos%2eltd%2euk%2facatalog%2fcatalogbody%2ehtml%26CatalogBody&WD=expanding&PN=Chronos_Catalogue_Miscellaneous_Milling_Accessories_101%2ehtml%23aSMA43#aSMA43

You can turn them down to various steps along the shank, so one can hold a few different sizes. Imagine doing it on the end of a blank MT arbor, it would be very easy to pop between lathe and RT on the mill. They are really dead easy to make.


Bogs

[raynerd]

Thanks for the suggestion John. Chris

[Darren]

I have used Arc's 5C expanding mandrels and can report they work wonderfully well.

Got me out of a fix when I needed to reduce a batch of sintered bearings buy half a thou 

I couldn't see any other way of doing it, they were scrap otherwise ... 

[raynerd]

You know I`ve been thinking about this and these would work a treat in a 2MT as I could use a sleave 3MT to work in either lathe headstock and then remove the sleve to work in the rotab. Only problem I can see is that the effective range 5.5mm as the smallest. This is still a little too large and would really need a working range from 4-8 mm. can you just confirm I am correct?

Chris

[raynerd]

I`ve been reading the other thread on making an expanding mandrel. Would it work for something as small as M4?

[bogstandard]

Would it work for something as small as M4?

Surely the way to do it is try it, if it doesn't work, you will have your answer.

There are some questions that just can't be answered because we have never done it, time for you to learn something by your own trial and error.

[raynerd]

Yes, I may give it a go although my fixed mandrel is working well and besides, the bore sizes for the wheels I need are 4mm, 6mm and 8mm so I know for sure that it won`t expand, probably not nearly enough, to even encompass two of these sizes. It will probably be as effective to make individual arbors for each size and build up a range of wheel holders in metric sizes. The Bergon clock wheel holders are just a straight shank style so clearly this method is used for a reason.
Thanks anyway - again, I`m trying to find one mandrel that will do a job but it looks like most people use a collection of sizes for different wheel bores.

[NickG]

So what's next Chris? Is this the main project now or are you back on the QCTP now?! 

Nick

[raynerd]

lol, now now 

I`ll be honest mate, it was going pretty well cutting the dovetails on the shaper but I`ve had a few issues getting access to with it not being at my house and it needs a bit of a looking at to get it running true. I still aim to make the QCTP but it isn`t my priority, I`m pretty enthused with my clock at present. I`m sure I`ll have a break in a few months when I have cut a few wheels and the QCTP may come back on the cards. It is nice to see people take interest in projects... I just can`t stop thinking about this clock at present, every second of every day!! I think I`m poorly....OCD?

 

[NickG]

 

I'm like that too ... mine is thinking about the flame licker though! The only way I get to sleep (and this is the truth) is running through the machining sequence in my mind for the remaining parts - but I always get side tracked and end up thinking from step 1 again and again and again! Having said that, I was reading my "Sweet Pea" book last night and haven't touched anything on that for 11 years -  I think I may be ill!  I need to 

When I think about it, there was my freelance electric loco idea, then I felt under vast pressure to make a rocking engine  , then I said I was definitely going to concentrate on the 3 1/2" loco restoration, then I started talking about a QCTP after seeing yours - then I went and started making a flame licker!! So I'm as guilty, if not more than everybody else! I have always loved flame lickers though. 

Really, I should have done the QCTP and it would have sped up all subsequent projects!

You're doing a good job, enjoy watching your projects unfold.

Nick