Harrison M300

[scottmk1]

@Shox Dr converted his to ball screw and reports no problems so definitely worthwhile investigating further

 

[Munkul]

No need to check the actual screw the rule is simple:

If the handle moves with the slide, it's a RH thread. If the handle does not move with the slide the thread is LH.

There are some exceptions but very very few.

Wow, you learn something new every day, i did not know this. Seems blindingly obvious now!

 

[pressbrake1]

No need to check the actual screw the rule is simple:

If the handle moves with the slide, it's a RH thread. If the handle does not move with the slide the thread is LH.

There are some exceptions but very very few.

Dsg with geared cross slide is!

 

[Pete.]

Dsg with geared cross slide is!

Geared handwheel is pretty much exactly what I was referring to.

 

[northwest]

@Shox Dr converted his to ball screw and reports no problems so definitely worthwhile investigating further

Yes he has and my next move is to contact him and see what type and size of ballscrew he used :-)

 

[scottmk1]

Yes he has and my next move is to contact him and see what type and size of ballscrew he used :-)

Good, pretty much sure he used 5mm pitch but will leave it to him to explain as I’ve not actually done it myself

 

[scottmk1]

Dsg with geared cross slide is!

What about the geared Gamet, Colchester, Harrison hand wheel assembly’s?

 

[Pete.]

Yes he has and my next move is to contact him and see what type and size of ballscrew he used :-)

In several posts on here he says he used a 1605 ball screw ( 5mm pitch) which begs the question is your cross-slide screw a 2-start thread? If your screw is 2.5mm pitch and you swap it out for a 5mm pitch then your dial will read half of the movement. Unless it's a 2.5mm pitch 5mm lead 2-start screw. The dial would read 0-5mm if so.

Or even to be really weird does your dial have both inch and Metric graduations or does the dial turn at a slightly different rate to the handle? Some metric Harrisons had dual dials, they used the standard inch pitch screw and the metric dial was internally geared to read correctly.

 

[Agroshield]

What about the geared Gamet, Colchester, Harrison hand wheel assembly’s?

They do not do anything specifically regarding the hand of the screw. What they do is make both the imperial and metric graduated dials read correctly. On these, if the screw is imperial, the imperial _dial_ is fixed to the screw and the gearing makes the metric _dial_ rotate.

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With the DSG geared cross slide, how do they accommodate backlash between the gears (so the handwheel doe not have a sloppy feel)?

 

[Agroshield]

It wasn't a suggestion, just the mention of another machine with a non-standard 2.5mm pitch thread.

Whatever it was, it is a good idea: find a machine with a screw of the correct pitch and hand and borrow it.

You mention above that you have inserts "if you want to try to make your own". We should note that those would only be good to him if they are left hand inserts.

 

[iNf]

They do not do anything specifically regarding the hand of the screw. What they do is make both the imperial and metric graduated dials read correctly. On these, if the screw is imperial, the imperial _dial_ is fixed to the screw and the gearing makes the metric _dial_ rotate.

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With the DSG geared cross slide, how do they accommodate backlash between the gears (so the handwheel doe not have a sloppy feel)?

On my m250 with dual dials the 2 outer gears both rotate but have different numbers of teeth

 

[Pete.]

On my m250 with dual dials the 2 outer gears both rotate but have different numbers of teeth
View attachment 449411

Which dial is attached directly to the screw? I bet it's the imperial reading one.

 

[pressbrake1]

What about the geared Gamet, Colchester, Harrison hand wheel assembly’s?

Those machines are white goods so no interest

 

[iNf]

Which dial is attached directly to the screw? I bet it's the imperial reading one.

It would seem so. On the metric scale a zero to zero revolution doesn't quite translate to one full revolution of the handwheel but on the imperial scale it does.

 

[pressbrake1]

You can over cut existing screw to even wear them split the nut or make new nut . If the screw isn’t hardened

 

[George Erasmus]

There is a seller on fleebay that rebuilds worn lead screws, if it has complex splines he cuts the spline end off and welds it to the new threaded rod
Ebay has listings for both sets of brass nuts
try this guy he may have a second hand one for sale

| eBay

 

[Pete.]

You can over cut existing screw to even wear them split the nut or make new nut . If the screw isn’t hardened

I have done this, documented here some while ago. It works very well if the screw is large enough to suffer the reduction in root diameter.

 

[daedalusminos]

IO was looking at making a new one for my M300 (long term project!) - as you say it's ACME threadform - I'm sure I either bought an insert or at least located one - maybe APT (might have had to contact them).

The gear is pinned and there's a keyway to cut, otherwise pretty straightforward.

Reltub34 on ebay used to sell new screws I think... worth contacting.

 

[George Erasmus]

IO was looking at making a new one for my M300 (long term project!) - as you say it's ACME threadform - I'm sure I either bought an insert or at least located one - maybe APT (might have had to contact them).

The gear is pinned and there's a keyway to cut, otherwise pretty straightforward.

Reltub34 on ebay used to sell new screws I think... worth contacting.

Yes he does the feed nuts but not the screws

| eBay