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MG MGA - Lathe Work On the Master Cylinder
|A while ago I mentioned that, for practice, I was going to try to resleeve an old master cylinder I have lying around.|
I am a relative new comer to lathe/mill work and I recently inherited (for a nominal fee) an old Myford Super Seven lathe in good condition.
Well, I am gradually getting there. I found it impractical to mount the master cylinder on the faceplate, so I have ended up mounting it on a vertical cross slide milling attachment (see photo). I now need to centre each cylinder with the chuck. I can do that without too much problem. What I really want to know is the type of boring tool arrangement I need to fit to the chuck/mandrel. Anyone out there to advise me? The boring tool needs to cut to a depth of about 4 inches and it looks about 1" diameter hole for the brass sleeve I have.
|Steve, I'm not expert, but why brass - because it won't rust? Stainless steel tubing is better, harder and should outlast brass. I have done this to all of my brake and clutch master/slaves and the s/steel can be beautifully honed. Try to shrink fit the sleeves as well if you can. Peter|
As the boring bar is to be mounted in the chuck, 3 jaw by the looks of it, it will rotate on a fixed axis. Therefore you need a means of bringing out the tool to increase the cut. To do this you need a boring bar that has a adjustable tool. I have seen homemade ones where the tool is held in a square hole by a grubscrew. You loosen the grub screw and pull out the tool to adjust the cut.
|With the chuck removed you should be able to fit a drill with a morse taper and sleeve. then similarly a reamer to the final size if it is 1", drill would be 31/32"|
problem would be not many people would have such a drill / reamer.
|R W McIntosh|
|Steve, 1st, I am not a machinist. I have never heard of doing what you are trying to do. I have seen a fixed boring bar and rotating the piece to be bored. So, I did a quick google and found that this is a relatively common practice. one example of an adjustable boring head would be:|
The screw-in tapered adapters are just below the boring head. I guess it is not that different than a mill on lying on it's side. You would have to figure which, if any, adapter would work with your lathe.
This may give you some ideas if you weren't aware of them in the first place.
|Steve. A boring bar, at least all that I have seen, would not extend into a 4" long hole. Drilling and reaming would be the preferred method as Ross mentions. As to the brass, or stainless, insert, it needs to be perfectly round. Many will vary by .001"-.002" on concentricity as they come from from the production mill. Thus, they may need to be skim cut to a slightly smaller size and the appropriate reamer for that size purchased. |
One of the problems with a three jaw chuck is run-out (i.e. wobble). With the best three jaw chucks you will have no more than .003" of run out with the one on my small lathe going .001". But, you need to know how much run out you have as this will affect the size of the hole as actually drilled and reamed when using the chuck as a tool holder. My big lathe has a four jaw chuck (each jaw is independently adjustable) and, when used with a dial indicator (clock gauge) to "dial in" the work piece the tolerances can be kept to under .0005" on parts that are perfectly round. Use a piece of drill rod or round tool steel and a dial indicator to see what run out is present with your chuck.
You're doing it the hard way. A good high speed steel machine reamer is the way to go. If you're planning on using silicone brake fluid then I'd advise against "shrink" fitting the sleeve. On the contrary, I'd size the sleeve sufficiently under-size so as to provide an adequate annulus for a full uninterrupted coating of anaerobic bonding agent such as Loctite 620. Otherwise the silicone will weep past the inevitable finish irregularities.
My father has written a number of books on Lathes. If you wish to discusss the options let me know and I will give you his contact details.
|Thanks for all the comments so far. All very interesting and informative. I have been speaking to an engineering supplier this morning (www.rdgtools.co.uk) and I am going to have another look at mounting the MC on the faceplate, possibly using the Keats Angle Plate. However, I need to see if the Myford can take a combination of this angle plate and the MC - quite bulky and may not have enough clearance: http://www.rdgtools.co.uk/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2erdgtools%2eco%2euk%2f&WD=688&PN=ANGLE_PLATES_AND_VEE_BLOCKS%2ehtml%23a688#a688|
Is this your Dad's work? I may like to pick his brains at some time, if only by email exchange. Not having an engineering background, even some of the terminology beats me. Took me quite a while to work out what 2MT meant. A lot of these guide books start off with many of the abbreviations and names etc as a given.
It is indeed one of his books.
If you provide me with an email I will put you in touch.
|Steve. You want a copy of "Machinery's Handbook", preferably either the paper back "Student's" version or a good used copy in hard back. It will contain a lot of information which will be of use to you. A couple of text books on basic machine tool operation are also a good idea. Most of these can be found used and at fair prices. There are also some machinist's forums on the web. If you are interested, I will ask a friend what ones he subscribes to.|
Face plate or a four jaw chuck is the way to go.
|The back end of the MC is an awkward shape and makes it difficult to mount. My 4-jaw is too small to hold it. Likewsie the standard Myford 7 inch faceplate will not take the width of the MC (offset when one of the bores is centred) and 2 right angle holding plates. I may invest in a 9 inch faceplate.|
Johnbray at focusrm dot co dot uk
|Sorry to bomb your list. I am a TR guy that strays to the other marques when bored.|
Steve-I made a fixture to machine brake&clutch cylinders in a lathe that bolts onto a 8" face plate. It you want some pictures and description please write.
Many years ago I remember seeing a video from White Post Restorations showing their re-sleeving process. I noticed that they machine a series of shallow grooves in the OD of the sleeve to retain a thread locking compound and and the sleeve was almost a slip fit in the cylinder.
|Berry, Yes please for pictures etc: stephen dot gyles at virgin dot net.|
I have just done some measuring. I have only 4cm (1.5") gap between the front of the face plate and the front edge of the ways (machined top surface rails on which the cross slide travels). This does not give much clearance for attachment brackets bolted near the edge of the faceplate. I may just get away with a Keat's angle plate. Otherwise, I will have to make something up as you did. As you will see from the photo, the standard Myford brackets, when offest, cannot take the MC and still provide clearance.
I am coming to to the conclusion that the Myford Super 7 is not large enough for this type of machining.
John, thanks for the address, will be in touch.
|Steve-Did you receive the pictures I sent?|
Just been looking at your email this very evening. Thanks for all the information.
|Steve-After looking at picture of an MGA master cyl., it looks like my fixture wouldn't be of much use. Maybe an angle plate or vise with a drill press using a reamer.|
This thread was discussed between 19/03/2008 and 26/03/2008
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