Boring Loco Cylinders

[ron]

Hi Everybody
I'm getting near to boring Simplex cylinders and would like opinions on the best way to go about this. Up to now any Stuart Turner cylinders I've bored have been mounted either in a four jaw or a face plate and bored with an indexable boring tool and finished them off with a home made lap. The Simplex cylinders are 1.5" bore X 3" long and I've doubts as to whether my usual method would produce a parallel bore as the Simplex cylinders are much longer than any ST ones I've done. Boring between centres looks not a bad bet but I've never done it and haven't found a supplier for a tool to do it, anyone any suggestions?
Cheers,
Ron

[lancelot]

Hello Ron,
G.L.R. DISTRIBUTORS LTD. do a between centres boring bar that would be suitable, I did the cylinder on the ''Coombes'' it was close to 3'' , it took about a dozen passes with the bar [not between centre type] the last few cuts at same setting to allow for spring, before I was happy with it.
I used ''between centre'' boring bars at training school many years ago, they can do a very good job but difficult to set, still have to allow for ''spring''.
All the best for now,
John.

[chameleonrob]

I made a between centres boring bar out of some MS bar, 6mm dia HHS and a grubscrew. I finished it to size with a 30mm dia boring head mounted on a length of 1" dia MS bar held in the 3 jaw, at that size the entire head went into the cylinder. I got mine from here www.chronos.ltd.uk/acatalog/ Reference #BH30MM

rob

[John Lee]

Ron, the only absolutely guaranteed way to produce parallel bores is a between centres boring bar.

I don't know what equipment you have, but in ME sizes you need to contend with tool springback, little bits of backlash etc etc which all conspire to put it out of you use a boring head, just a bit, but enough so it does not "quite" work.

If you think about it, providing you have not got a worn lathe bed, it cannot fail.

Most between centre boring bars have crude adjustment so its hard to work to the last half thou, but you just make your pistons to fit, a much easier job.

Regards,

John

[steammadman]

Get you hands out of your pockets and make a between centres boring bar

you only nead a peice of 3/4 round bar, centre at each end, and an old ,broken
slocombe drill ground to shape.
hang on to your money you might need it at HARROGATE.
(even if its only to get a round in !!!!!)

[Myford Matt]

George Thomas has some very nice designs in 'The Model Engineers Workshop Manual - G H Thomas'. It's available from Hemingway Kits, as is a kit for a set of boring bars.

It's a book everyone should have; well everyone into ME.

MM

[jhaines]

One thing has always puzzled me about mounting cylinders on the cross slide and using a between centres boring bar, if your cross slide has even the slightest backlash surely you would end up with an oval cylinder, Is it just a case of tightening all the gib strips?

[Myford Matt]

I'd lock the cross-slide, or rather will when I do my 57xx's cylinders.

MM

[Shawki Shlemon]

Hi Ron
Visit my thread on page 6 in general chat and I explained how I do it with home made tools between centres with photos .

[Boadicea]

Sorry about this diversion (couldn't resist it!) , but isn't the answer to boring loco cylinders to paint them in a pretty colour, possibly with flowers on them? Ho, ho, ho, LOL ;D

Back to the serious stuff then ....

Regards, Bo

[chameleonrob]

johnleepbs said:

Ron, the only absolutely guaranteed way to produce parallel bores is a between centres boring bar.

John

how do you mean? the boring head I used was mounted on 1 " dia bar which was held in the three jaw chuck on the lathe, the cylinder was mounted on the lathe saddle (not the cross slide) as any tool spring back etc. would be constant (as in a between centres boring bar) and as the mounting was solid as possible and I used it for finishing not roughing it came out as round, acrute and as smooth as possible.

rob

[Noddy]

I was looking at boring bars on the hemmingway site the other day and they had a kit complete with micrometers for setting them. A few years ago, I got a flyer at Harrogate for a ready made between centres bar from Arrand tool co.

Hope this helps

[John Lee]

chameleonrob said:

johnleepbs said:

Ron, the only absolutely guaranteed way to produce parallel bores is a between centres boring bar.

John

how do you mean? the boring head I used was mounted on 1 " dia bar which was held in the three jaw chuck on the lathe, the cylinder was mounted on the lathe saddle (not the cross slide) as any tool spring back etc. would be constant (as in a between centres boring bar) and as the mounting was solid as possible and I used it for finishing not roughing it came out as round, acrute and as smooth as possible.

rob

I mean.. if you use a boring tool, and your cylinder is mounted on a faceplate (ignore doing it with a mill, some have not got the gear)

You will get tool springback, plus the backlash in your crosslide, plus the backlash in your lathe bed.

You can send the tool back and forth, but for what you think is a finishing cut, it will just rub.

So, a between centres boring bar (about an inch diameter, much stiffer than a boring tool), only one dimension (your lathe bed) gives you backlash or defection, and if its in good nick, none.

But if you have done it with your setup Rob..excellent..

Regards,

John

[Laurie_B]

keithanderson said:

A few years ago, I got a flyer at Harrogate for a ready made between centres bar from Arrand tool co.

Hope this helps

I was just looking at the Arrand engineering catalogue,and they do supply two sizes of between centres boring bar.
The smaller is 13/16" dia,the larger is 1-1/4" dia.These will produce bores up to 1-1/2" and 2-3/4" respectively.
And they have micrometer adjustment (in increments of 0.0005")to the toolbit.
Although Arrand aren't exactly cheap,I've bought a few items from them over the years and their products are excellent.

[steammadman]

We seem to have an awful lot of model engineers these days with an awful lot of
money to waste on fancy tools etc,in the old days we had to make as many tools
as we could, wages were only 1 AND 9d an hour , in propper money.

[Myford Matt]

I'd like to echo your comments Laurie. Arrand's stuff isn't cheap, but it is really well made. I have their boring bars and they are very good quality.

Do note that they take carbide tips - not HSS. The only problem is that replacements are pricey - not Arrand's fault, it's an item they buy in.

The chap that runs it used to make tooling for Jones and Shipman and it shows in the quality of the ground work.

I know it's an expensive sentiment to hold, but it's nice to still be able to buy British-made tooling made to high standards.

Matt

[Laurie_B]

Quite agree Matt.I have their boring and facing head and their collet set.
Excellent quality,and although they are expensive,their tooling will last years.
The between centres boring bar tool bits are indeed very dear,it looks as the carbide tipped bit is made as part of into the micrometer setting part.
Myfords sell a more conventional bar that looks as if it takes HSS tool bits,but without the micrometer setting.

[Noddy]

Here Here! If the quality and service is there, then we may as well support companies like Myford, Arrand etc.

I know that in the past, many of the tools had to be home made, but was that through financial necessity alone, or were they simply not available otherwise?

I would love to have the time to experiment with a bloomery, smelting iron, and making all sorts of tools, but I just don't have it, nor do many others. we have to work longer and harder to support not just our living standards, but also that of the burgeoning mandarin class (DEFRA has 14 bureaucrats administering agriculture for every 1 farmer, and that is just 1 example).

However, the time that we are working buys a lot more time in the far east for manufacturing run of the mill tools and, that in turn pays my wages finding the coal, iron, Dolomite, fluorspar etc to make them out of.

If someone like Arrand can make a living making good quality useful tools at a reasonable price (chances are he is also having to pay for 3 times his workforce in Bureaucratic burden), then I for one will buy from him.

Rant over
Keith

[John Lee]

keithanderson said:

I know that in the past, many of the tools had to be home made, but was that through financial necessity alone, or were they simply not available otherwise?

Nope, how many locos are you building?

A between centres boring bar is easy to make. Providing your tailstock and headstock are set true, it is bound to make a parallel bore if your lathe bed is ok.

A screw at 40tpi gives your thou adjustment, just pass a micrometer over it. It's not financial necessity, just common sense, why pay lots for a tool you will use few times??. Decent files are a better investment, now how many times do you reach for them?? Or drills, or taps, or your hacksaw?

So Ron, back to your original post. Mount it on your crosslide if you can, and use a homemade between centres boring tool. Perfick in "Only fools and horses speak"

John

[SteveW]

Guys,

It occurs to add that if you're using a Myford without a gear box then getting a low/smooth enough saddle travel speed is difficult. I found that even with the default set of gears I could only get down to somewhere like 120 tpi which isn't quite enough for a good finish.

I then found Myford did a little compound gear (a different one for ML & S7) that sits at the beginning of the set. I've found this to be one of my best buys from Myford and gives a good finish.

I can't remember how much it was, somewhere between 10 and 15 quid a while back.