Fitting suspension units

Includes workshop practice, painting and weathering, model photography etc.
User avatar
David B
Posts: 1097
Joined: Sun Jul 20, 2008 5:30 pm

Fitting suspension units

Postby David B » Mon Nov 02, 2015 3:10 pm

Preparing the bits for suspension units is not one of my favourite pastimes. Cleaning, soldering, filing and milling the small bits gets to the fingers, especially holding the axle boxes to open out the back and let the bearing move up and down.

I have been using a milling bit I got in a pack from Axminster Tools, in a Dremel. It works very well (I set it a slow as I can) but as soon as it warms up, it clogs with the white metal - a familiar scenario. Cue the scalpel to lever it off and then get half the next slot done before repeating the process.

If it is the heat that makes the bit clog up more readily, then why not try cooling it? I tried a small pot of water and dipped the bit in before applying it to the axle box. What a difference! I can now get a whole axle box grooved without the bit getting any white metal stuck to it which has speeded up the whole tedious process.

The water, I expect, is also acting as a lubricant, but without analysing it too much, I have found a way of getting the job done more quickly and the swarf not flying off to any great distance.

milling_1134.jpg
The paraphernalia and pile of swarf.
milling_1134.jpg (120.16 KiB) Viewed 4578 times

milling_1135.jpg
The milling bit. This is about 2.25mm diameter.
milling_1135.jpg (51.95 KiB) Viewed 4578 times

milling_1136.jpg
The finished slots. I have gone down to the depth of the cast hole, the bottom of which can just be seen.
milling_1136.jpg (114.62 KiB) Viewed 4578 times

Mark Forrest
Posts: 40
Joined: Mon Nov 28, 2011 6:44 pm

Re: Fitting suspension units

Postby Mark Forrest » Mon Nov 02, 2015 6:56 pm

Thanks for sharing that info, think I need to get myself a couple of those milling bits, they look really useful.

Joe Newman
Posts: 49
Joined: Tue Aug 11, 2009 8:25 pm

Re: Fitting suspension units

Postby Joe Newman » Mon Nov 02, 2015 7:19 pm

Thanks for the tip about cooling the milling bit David. Like you I have spent too much time scraping white metal off them.

Joe

User avatar
Flymo748
Posts: 2171
Joined: Sun Jul 20, 2008 6:00 pm

Re: Fitting suspension units

Postby Flymo748 » Mon Nov 02, 2015 7:24 pm

I'm just wondering if talcum powder or French chalk would work just as well...

I'll have a test next time I'm doing some milling of white metal and report back.

Cheers
Flymo
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

User avatar
David B
Posts: 1097
Joined: Sun Jul 20, 2008 5:30 pm

Re: Fitting suspension units

Postby David B » Mon Nov 02, 2015 7:54 pm

Flymo748 wrote:I'm just wondering if talcum powder or French chalk would work just as well...


It might depend on whether or not you keep them in the fridge.

Mark Forrest wrote:Thanks for sharing that info, think I need to get myself a couple of those milling bits, they look really useful.


I bought a set of 5 like these, Mark. See: Axminster Power Tools.

User avatar
Flymo748
Posts: 2171
Joined: Sun Jul 20, 2008 6:00 pm

Re: Fitting suspension units

Postby Flymo748 » Tue Nov 03, 2015 8:14 am

David B wrote:
Flymo748 wrote:I'm just wondering if talcum powder or French chalk would work just as well...


It might depend on whether or not you keep them in the fridge.

Mark Forrest wrote:Thanks for sharing that info, think I need to get myself a couple of those milling bits, they look really useful.


I bought a set of 5 like these, Mark. See: Axminster Power Tools.


Ah, so you are thinking that it is the cooling effect that is stopping them clogging, rather than the water acting as a lubricant and stopping the whitemetal binding to the cutter...

I was thinking that it was the latter, rather than the former. Hence my thoughts on French chalk (of which I have a bag sitting around from casting parts for 5522 Models).

Those cutters on the Axminster site look like excellent value, so I've popped an order through for two sets. That will keep me going for quite a time.

They're likely to replace the somewhat nasty ones that I have taken out of a Maplin set of "200 rotary tools" which consists of 150 slitting discs, 40 polishing mops, and 10 tools that are actually useful! Still, for a tenner I can't complain...

I'll see how I find the new cutters when I next have to do some wagons.
Cheers
Flymo
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

dal-t
Posts: 615
Joined: Mon Jan 11, 2010 8:06 pm

Re: Fitting suspension units

Postby dal-t » Tue Nov 03, 2015 10:09 am

When drilling white metal, I was always told to use spit (saliva), which Wikipedia tells me is 99.5% water; but subsequent advice to switch to Vaseline (literally water:oil) proved both more effective and more hygenic. It would be the first thing I would try if attempting to mill the material now, but having indulged in that game all too often in the past, opening up OO-designed whitemetal footplates/splashers to take a finescale chassis, I was hoping in the era of multi-gauge etched brass it was a practice I wouldn't need again. Hence I have been waiting for Bill Bedford to arrive with his usual comment that you really don't need to remove that much material to make sprung suspensions work, so that I could move on sighing with relief. Personally, when building wagons I've never opened axleboxes up that dramatically, a few twists with a suitably sized (i.e. significantly over-large) round file has usually sufficed.
David L-T

User avatar
Will L
Posts: 1643
Joined: Sun Jul 20, 2008 3:54 pm

Re: Fitting suspension units

Postby Will L » Tue Nov 03, 2015 4:21 pm

Rubbing chalk into a file does help to stop it getting clogged with white metal, whether this would work with anything with teeth as course as one of these cutters I'm not sure.

Spit is certainly a good lubricant when hand drilling white metal, or any other metal for that mater. I suppose sufficient spit would do on a cutter but frankly I would not be putting one of those in my mouth while it was still attached to power tool. I think David's little disk of water is a good idea, but perhaps it could be improved by adding a little something else in it to make it gel a bit.

I agree with dal-t that I don't find it necessary to excavate anything like as much as David has.

Terry Bendall
Posts: 1619
Joined: Sun Jul 27, 2008 7:46 am

Re: Fitting suspension units

Postby Terry Bendall » Wed Nov 04, 2015 8:22 am

The use of cutting fluids when using machine tools is well known. There was a very brief mention of it in the series that I wrote about using machine tools. In engineering there are three reasons for using cutting fluids, one is to keep the cutting tool cool, the second is to lubricate the cutting action which helps to give a better finish and the third is to wash away the swarf or chips from the cutting process. David has clearly found the need for the third application. Checking in my reference books there is no mention of using cutting fluids when machining white metal but that does not mean it cannot be done. In this application water would be adequate as David has found but a water based soluble oil, as might be used when turning steel in a lathe, would probably be just as effective.

And Will is quite correct about using chalk to stop the teeth of a file clogging up, especially when filing white metal and pewter.

Terry Bendall

mikeknowles
Posts: 39
Joined: Mon Dec 01, 2008 8:58 am

Re: Fitting suspension units

Postby mikeknowles » Wed Nov 04, 2015 12:48 pm

[quote="David B
I bought a set of 5 like these, Mark. See: Axminster Power Tools.[/quote]

Having read the post yesterday I ordered a set and they've arrived this morning. Can't ask for better than that!

User avatar
steve howe
Posts: 510
Joined: Sun Feb 01, 2009 10:16 pm

Re: Fitting suspension units

Postby steve howe » Wed Nov 04, 2015 5:52 pm

I wonder if powdered graphite mixed with water might be a help when milling whitemetal?

Steve

billbedford
Posts: 670
Joined: Tue Oct 02, 2012 2:40 pm

Re: Fitting suspension units

Postby billbedford » Thu Nov 05, 2015 10:16 am

David B wrote:I have been using a milling bit I got in a pack from Axminster Tools, in a Dremel. It works very well (I set it a slow as I can) but as soon as it warms up, it clogs with the white metal - a familiar scenario. Cue the scalpel to lever it off and then get half the next slot done before repeating the process.


Oh dear, oh dear, oh dear. If you insist on using that excavator bit you are going to get yourself into exactly this sort of trouble. Dental burrs are tools of delicacy and refinement, which allow skilled operators the ability to remove a minimum amount of material in exactly the right places. The two rules for getting the best out of your bit are:

High speed & the lightest of touches.

i.e. these bits cut by speed not pressure.

Personally I would use a 1.5 or 1.8 mm ball or a similar sized fine cylinder burr for this sort of work.

It looks to me as if you have cut the backs of these castings much deeper that needed compared to the amount the bearing protrude from the w-irons. And I would suggest that it is a really good idea to chamfer the edges of the cuts in the axleboxes as this will tend to keep any glue/solder film away from the bearing slots in the w-iron.
Bill Bedford
Mousa Models
http://www.mousa.biz

User avatar
David B
Posts: 1097
Joined: Sun Jul 20, 2008 5:30 pm

Re: Fitting suspension units

Postby David B » Thu Nov 05, 2015 10:52 am

billbedford wrote:Oh dear, oh dear, oh dear. If you insist on using that excavator bit you are going to get yourself into exactly this sort of trouble. Dental burrs are tools of delicacy and refinement, which allow skilled operators the ability to remove a minimum amount of material in exactly the right places. The two rules for getting the best out of your bit are:

High speed & the lightest of touches.

i.e. these bits cut by speed not pressure.

Personally I would use a 1.5 or 1.8 mm ball or a similar sized fine cylinder burr for this sort of work.

It looks to me as if you have cut the backs of these castings much deeper that needed compared to the amount the bearing protrude from the w-irons. And I would suggest that it is a really good idea to chamfer the edges of the cuts in the axleboxes as this will tend to keep any glue/solder film away from the bearing slots in the w-iron.


Oh dear. ;) This is not a dental burr, Bill - it is a milling bit and not one I would like anyone putting in my mouth! It is the smallest milling bit I have found of this shape.

I take your point about speed, but the other side of this is that if is catches, it spins off and cuts where it is not wanted. This is a job done by hand and I find I have greater control at a slower speed. Does not the high speed generate more heat and melt the white metal, so increasing the clogging of the bit?

I have not used a ball because the back of the bearing that protrudes is parallel sided. I am using the waisted ones which need a file across the back first. I may well be excavating plenty deep enough, but the bit of the bearing that protrudes through the W iron does vary - not all waisted bearings are made to the same measurements - and I have had them catch, so now I make sure I leave plenty of space.

As for soldering, with a light touch, a pointed iron bit and small amount of solder I have never got solder anywhere near the bearing or the slot on the W iron. I do pass the file over the back of the casting to remove the grey coating and solder on to clean metal.

User avatar
David Thorpe
Posts: 811
Joined: Tue Oct 21, 2008 11:13 pm

Re: Fitting suspension units

Postby David Thorpe » Thu Nov 05, 2015 2:23 pm

I sympathise, David. Like you I use waisted bearings. Like you, I've found that when I've only removed a small amount from the axle box, eg merely to the depth of the bearing, they still catch and so, again like you, I end up making a much bigger hole, rather like the ones you've illustrated, so as to allow space above and at the sides as well. Then the bearings don't catch.

DT

Terry Bendall
Posts: 1619
Joined: Sun Jul 27, 2008 7:46 am

Re: Fitting suspension units

Postby Terry Bendall » Fri Nov 06, 2015 8:30 am

David B wrote:Does not the high speed generate more heat and melt the white metal, so increasing the clogging of the bit?


I think this would be highly unlikely David however fast the bit turns.

billbedford wrote:If you insist on using that excavator bit you are going to get yourself into exactly this sort of trouble.


I think this is an instance of different people having different ideas on how to do a particular job. A burr will remove metal but it may not be the best way of doing the job just a brass can be ground on a grinding wheel but it will not do the wheel a lot of good. :) A small milling cutter does have to be used with care since it can snatch and end up in the wrong place which is where a slow speed may help.

Terry Bendall

User avatar
Guy Rixon
Posts: 583
Joined: Sun Mar 27, 2011 6:40 pm

Re: Fitting suspension units

Postby Guy Rixon » Fri Nov 06, 2015 9:49 am

David Thorpe wrote:I sympathise, David. Like you I use waisted bearings. Like you, I've found that when I've only removed a small amount from the axle box, eg merely to the depth of the bearing, they still catch and so, again like you, I end up making a much bigger hole, rather like the ones you've illustrated, so as to allow space above and at the sides as well. Then the bearings don't catch.


I find this problem too, from two causes. First, the vertical centre of the hole cast into the axlebox doesn't quite match the central position of the axle when the vehicle rides on its springs. Secondly, being inept in assembly, I find it easy to displace the axlebox horizontally by a couple of tenths of a millimetre. I always carve in more clearance than the ideal case suggests. "Lightly countersinking" the hole does not work for me.

billbedford
Posts: 670
Joined: Tue Oct 02, 2012 2:40 pm

Re: Fitting suspension units

Postby billbedford » Fri Nov 06, 2015 10:39 am

David B wrote:Oh dear. ;) This is not a dental burr, Bill - it is a milling bit and not one I would like anyone putting in my mouth! It is the smallest milling bit I have found of this shape.

Different vendors, different names: https://www.cousinsuk.com/product/cylinder-cross-cut-parallel-af-119315
and there are dental technicians as well as dentists who use this sort of equipment.
I take your point about speed, but the other side of this is that if is catches, it spins off and cuts where it is not wanted. This is a job done by hand and I find I have greater control at a slower speed.

That is why it is the wrong tool for the job. You need need a bit with finer teeth what ever the shape of the head.
Does not the high speed generate more heat and melt the white metal, so increasing the clogging of the bit?

Clogging is a symptom of using too much pressure. and not enough speed.
I have not used a ball because the back of the bearing that protrudes is parallel sided. I am using the waisted ones which need a file across the back first. I may well be excavating plenty deep enough, but the bit of the bearing that protrudes through the W iron does vary - not all waisted bearings are made to the same measurements - and I have had them catch, so now I make sure I leave plenty of space.

The slot in the axlebox still has to be wider than the slot in the w-iron to allow for any mismatch when placing the axlebox.
Of course, the other reason suspensions jamb is because the axle/bearing combination can be slightly wider than the space between the w-irons.
Bill Bedford
Mousa Models
http://www.mousa.biz

User avatar
David B
Posts: 1097
Joined: Sun Jul 20, 2008 5:30 pm

Re: Fitting suspension units

Postby David B » Fri Nov 06, 2015 11:17 am

Thank you for the link, Bill. Very useful.

I am no convinced about some of the other issues but will experiment and see what happens. The best thing with the white metal would be to have the slot cast, but I think there would be more chance of seeing pigs fly.

User avatar
Will L
Posts: 1643
Joined: Sun Jul 20, 2008 3:54 pm

Re: Fitting suspension units

Postby Will L » Fri Nov 06, 2015 1:55 pm

...And if ou look at the end of the second page Bill linked to you find Burr Lubricant Wax which seems to take us full circle.


Return to “Tools and Techniques”

Who is online

Users browsing this forum: No registered users and 2 guests