Rebuild it sell it on. When I started looking for one, I enquired with one of the companies that claim to rebuild them, starting cost most £7.5k. All that got you was a wash and brushup.
A full grind and you are looking at £10-12k+
Trouble is you might fall for it again
You could have a new V350 for £11,000. Ah, that M300 is 1,000mm.Rebuild it sell it on. When I started looking for one, I enquired with one of the companies that claim to rebuild them, starting cost most £7.5k. All that got you was a wash and brushup.
A full grind and you are looking at £10-12k+
Trouble is you might fall for it again
Well, I got myself a Harrison M300, 1000mm between centres & it's in need of a proper rebuild.
I think the bed etc will be off to Slideway Services for a regrind once I have finished stripping it & I'm looking to replace quite a few parts like feed screws & nuts, a few of the control knobs and seals/gaskets where needed.
The head runs nice & quiet so I'm hoping that it doesn't really need any new parts however I will give it a good clean out.
The first thing I want to attend to is the cross feed screw & nut. Mine is worn to the point that the crown of the thread is pointy! The adjusting wedge for the nut is missing & can only assume that the threads in the nut are goosed too. The micrometer dials are the dual imperial/metric type, these have been well abused & basically I think they are scrap so I might look into getting plain metric ones. The lathe has a DRO fitted so that takes care of any conversion stuff.
So, what material is most suitable for making my own feed screw? I have plenty silver steel, although I will need to check length, and I have another lathe to use for turning & screw cutting. If silver steel is no good, what is? What about the nut, would a one piece nut do the job or am I going to have to make a 2 piece nut with a wedge as per the original? The top slide screw & nut will probably be the same so that will receive the same treatment.
Pics to follow once I've tidied up the workshop!
Looking at the screw pictures I take a guess that they are single start. Kingston sell there screw by 1 metre or 3 metre lengths but if you ask nicely like I did they may find a short offcut for you.Well some photos as promised
Lathe in the workshop partially stripped
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The front of the front Vee way is in good enough shape
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However the flat ways have suffered a bit of scoring & so have the backs of the Vee's
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The ways on the cross slide arent too bad but they do have a little scoring. You can see where the T nut for the compound slide has been abused & broken a piece of the cast lip off.
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Cross feed screw un-worn area.View attachment 73432
Cross feed screw worn area.
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Dual micrometer dials are a bit scabby & had been assembled with a BFH & chisel by the looks of things.
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The bed on Chipmaster is considerably heavier than on an L5The chipmaster is a different ball game as it is an older model witch you would compare to a Harrison L5 / 9".
The modern equiverlant would be a student 3100.
The chipmaster was more of a lighter machine with a high spindle speed and variable speed drive built more towards smaller precision component manufacture.
Thems trapezoidal, he will want Acme. http://www.kingston-engineering.co.uk/downloads/standard-screw-datasheet.pdf
What diameter is the crossfeed screw? looks like Acme trapezoidal? this is fairly cheap to buy.
What most professional bodgers do is part off the control portion of the screw and drill both new screw and original control shaft or drill one and hole in side to drift in taper or roll pin. Drilling both and connecting with short length of rod then silver brazing seems to work well, really well. You are just replacing the threaded portion.It's a single start thread, 16mm diameter. The overall length is about 450mm and the threaded portion is 200mm long. The rest of it is 15mm diameter so getting a length of lead screw of the correct thread wouldn't work as there would still be some of the thread left on the 15mm diameter section.
Abssac have ex stock multi-start screw but at 2G fit, lead accuracy a little lazy at 0.006/FT. If I can dig out the bookmarks from another computer there is a supplier in the West Midlands that supplies 3G multistart in the usual sizes.If it folowed its predecessors, the 5A 140 etc then it will be a twin start thread. Tried for yonks to get a bronze nut for the boring table off the shelf, the 140 is def twin start, and I never found a twin start supplier.
Stan
It's a single start thread, 16mm diameter. The overall length is about 450mm and the threaded portion is 200mm long. The rest of it is 15mm diameter so getting a length of lead screw of the correct thread wouldn't work as there would still be some of the thread left on the 15mm diameter section.
I suggested parting off the old control section of spindle, boring hole in end, parting off correct length of screw then boring hole in that. Fashion dowel of correct length, flux all and silver braze.Hmmm! would a 20mm thread do it and turn the ends down to the required diameter then turn the thread down to 16mm,the thread has already been done so turning it down shouldn't pose a problem?