Harrison M300 Thread Dial Indicator (Imperial)

I have recently acquired an elderly (1952) Harrison M300 lathe. It is generally in good condition considering its age. However it is missing Pt/No 304.172 collar for TDI and Pt/No 304.170 16T gear (imperial) that engages with the 4TPI leadscrew. Anyone have these lying around, or would someone kindly let me have the dimensions so that I can make them?

Thanks in advance

1952, M300?

Hello Shaun

I have already had that queried

The serial number is 154393 I got the date from a website list. There is a slight discrepancy between the number on the switch plate and the number on the bed. The last digit on the number on the bed seems to have been overstamped. Happy to have corrections/further information.

Regards

Tommy Hutcheson (larneyin)

The Harrison M300 series was first manufactured in 1971, I think Tony's site at lathes.co.uk will confirm this.

For spare parts, contact the 600 group who are Harrison HERE ( http://www.600uk.com/products/harrison-centre-lathes/) first as they might be cheaper than you think. Might be eye watering too, but best ask. It always amuses me when I see genuine second hand M300 Fixed Steadies go for sale on ebay for three or four hundred quid. They are £270 brand new from Harrison.

edit:spelling

Edited By pa4c pa4c on 02/03/2018 19:04:30

Hi Tommy I think you will find that the last two digits are the year No 1993

David

Many thanks to you all for your responses

Closer scrutiny of the serial numbers list showed that I was on the wrong model - another senior mement

Will contact 600 group, but would prefer to have a go at making them just for the hell of it

Tommy

Having recovered from a bug that flattened me a couple of weeks ago, I set out to make a new cog for the DTI on my Harrison M300 (Imperial) lathe using the invaluable information provided by John Brookes of the Harrison Users Group.

The first attempt was a bit of a fiasco but served its purpose as I realised that it would be much simpler to make a single component using the DTI spindle as a mandrel rather than the original separate collar and cog.

A suitable length of 40mm diameter Delrin was cut and bored 3/8" to fit the spindle. The keyway in the spindle is 1/8" so, using a piece of 1/8" square tool steel ground to a cutting chamfer at one end, I was able to press the blank onto the spindle cutting the way in the Delrin blank as it went.

The outside diameter was turned down to 35.5mm and the shoulder to 7/8" dia x 3/4" long in accordance with John's information

An extension plate was mounted on the shaper box to provide enough length to mount the dividing head, chuck and spindle. The dividing head was angled at approximately 5deg which was what I had measured roughly from the leadscrew

The chuck was then transferred from the lathe to the dividing head and a jack made from a scrap piece of aluminium was mounted to support the outer end of the spindle

I had no information about the profile required for the cutter, but using John's photographs and a bit of "guesstimation", I ground a shaping tool to what I thought would do, given the undemanding nature of the profile

So, with fingers crossed, the first cut was made to the depth given by John

This went well, so, with great concentration, the rest ot the cuts were made

It is always a relief to complete the last cut without any disasters, especially when you arrive back to where you started!

The finished article

And the bonus is - it works!

With many thanks to John and all the others who responded to my request for information

A result! Far cheaper than buying the part from Harrison and will last for years.

Hi there.

Bit late joining this thread but suddenly had to remember how to cut threads on a lathe the other day.
One problem was that previous users of my M300 had decided to loose the small gear wheel. pin and bush on the DTI

Looked for a replacement in the usual places including Harrison's themselves but they were wanting silly money.BTW I guess you will all know that small Harrsion lathes are all sourced via Taiwan.

Somebody recommended HPC Gears in Chesterfield and they suggested that I try a 16 tooth gear to run up and down the imperial 4tpi lead screw. Part No. ZPG2-16

I turned up an new bush and drilled the nylon gear to accept the 1/8"dia pin.

(Is it my imagination or is this device a mixture of imperial and metric measurements?}

Works just fine for others in a similar boat.

Gear wheel plus post and packaging and vat was £22.

Somewhat better that the £100+ prices I had seen.

Cheers

Malcolm

Seen plenty on ebay from £10 upwards and no cheap plastic.

1993 would be a proper English build up Heckmondike, newer ones the last 20 years plus certain parts if not all are chinese. So go for a quality M300 Made in England.