Denham junior Manual

[Donald BlakleyParticipant @donaldblakley76520]

Hi I'm new here.

Last night a Denham junior lathe fell into my lap. Its many years since I have owned or used a lathe and I'm wondering if anyone could point me in the direction of where to get a manual for it.

I used to have a beautiful Smart and Brown but had to part with it due to space issues. I have been toying with getting a small lathe again for some time and a chance conversion led to me driving 90 miles to collect a Denham junior mk2 that was going to be picked up by the scrap man today in exchange for some beer tokens.

It looks fairly good but very dirty. Possibly missing some change gears and the gap piece for the bed. Still taking stock.

[Donald BlakleyParticipant @donaldblakley76520]

[MeunierParticipant @meunier]

Hello and welcome Donald,
lathes.co.uk has a write-up on the Denham Junior Mk2 here **LINK**
and lists machine tool manuals although that function wasn't working just now so can't tell if the Denham is included.
DaveD

[Roger ClarkParticipant @rogerclark]

Hi Donald, welcome to the forum and the Denham Junior gang There are a few of us here although I think we keep it a bit quiet

I've nearly finished restoring mine, just have a qctp to complete and install a 1.2kw 3 phase motor and vfd

I think I have a pdf copy of the manual if you pm me your email address.

Regards

Roger

[Neil WyattModerator @neilwyatt]

Welcome to the forum Donald.

Good job it wasn't a DS&G that fell on you, we might have had to send an ambulance round

Neil

[Donald BlakleyParticipant @donaldblakley76520]

Thanks for your replies guys. Forgot to thank you all in advance yesterday because I was so excited.

Reassembly is commencing today after I get it up a flight of stairs. An ambulance may yet be required.

[Roger ClarkParticipant @rogerclark]

Ha ha been there done that…. would offer but it's my back you know, think it was getting my lathe up a flight of steps!!!

[Donald BlakleyParticipant @donaldblakley76520]

Job done I'm uninjured but one of my assistants may never have children after getting battered in the plums with a 3×3 wooden post as the lathe slipped off it! Funniest thing I've seen in ages!

[Donald BlakleyParticipant @donaldblakley76520]

I was in about the head gear today. The low speed pinion on the intermediate shaft if fairly buggered due to people trying to put it in gear when running. Do people break lathes?

[Neil WyattModerator @neilwyatt]

Posted by Donald Blakley on 13/10/2018 15:38:16:

Do people break lathes?

This forum would be much less active if they didn't…

Neil

[Martin ChamberlainParticipant @martinchamberlain57475]

Hi Folks,

I am a newbie to this site and not that familiar with forums in general so please be forgiving of any faux pa's (?)..

I have owned a Denham Mk2 junior for about 25 years (Keighley lifts badge) and have only ever really used the basic functions barely touching the sundry levers apart from engaging the lead screw. I was always too worried about breaking it..

I now wish to do some thread cutting (40mm x 9tpi) and do not really understand the Table (Brass plate) concerning the Gears placement. I do seem to have the full compliment of gears and have watched as many (not really relevant..) YT vids I can find and still not really much the wiser..

My problem is I am not an engineer so do not understand much of the technical language or abreviations used. Also many parts seem to have a number of different names.

If a copy of this PDF Manual is available I would be an extremely happy recipient..

Specifically, if someone could explain the —- marking on the brass Thread plate when refering to which gears go on the 'Banjo' arm..? As other gear trains show 2 x different toothed gears on the same shaft I am assuming it means 2 the same..? Confused. I have seen pics of this plate on this Denham topic but I dont know how to link things yet..

If this topic has been covered do please point me to the thread.

Thanks Martin C

[Brian WoodParticipant @brianwood45127]

Hello Martin,

I might be able to help you with the gearing you need to get the pitch of 9 tpi you want to achieve.

You need to arrange change gears of 25 and 50 as drivers, together with 70 and 40 as driven wheels. The "gearbox" needs to be set to the mid position. The pitch generated will be 0.1116 inches which is 8.96 tpi.

I don't know the lathe at all but I assume gears can be connected to each other on the same shaft to give compound ratios.

Arrange 25 as the first gear in the chain to drive 40 which is coupled to 50 to drive 70 as the leadscrew wheel.

Regards Brian

[Brian WoodParticipant @brianwood45127]

Hello again Martin,

I have since looked at the photos and description in Tony Griffiths website lathes.co.uk and the set up is even simpler than the one I described.

Position A on the gearbox with change wheels of 40 driving 90. That will give you 9 tpi exactly. 90 goes on the one described as Guide Screw.

Sorry to have muddied the water to start with

Regards Brian

[Martin ChamberlainParticipant @martinchamberlain57475]

Hello Brian,

Many thanks for your help. I think your 1st response was helpful inasmuch as my understanding the gearing going from A – C via B..

My issue was with what does the ' —– ' on B mean.. on the chart/table shown?

I think it means.. it doesn't matter which single gear goes on the banjo arm as it is just a direct transfer as opposed to a change if a second gear with more/less teeth was also added.. Compound..?

So as you say in the second response.. it is actually even simpler.. 40t on the Spindle drive to 90t on the gearbox drive via…whatever gear fits..?

Am I in the right area..?

Regards

Martin

[Brian WoodParticipant @brianwood45127]

Hello Martin,

Yes indeed, you have worked it out correctly—whatever fills the gap as a joining gear will do.

Bear in mind that interposing a gear here will reverse the direction of drive to the leadscrew; the website photos don't show the more traditional tumbler reverse gears on the drive down from the main spindle. You have the lathe and may know the secrets involved but if it is a problem, put two smaller wheels as idlers in the space instead.

Regards

Brian

[Martin ChamberlainParticipant @martinchamberlain57475]

Hello Brian,

Excellent .. Thank you Brian.

My Lathe does not have the 'Tumbler gears' you mentioned but I have seen them on another Lathe on one of the YT vids I watched so understand what you mean.

I believe there is a forward/reverse option for both 'out' drives on the gearbox so shouldn't be a problem.

I am curious why there are two revolving shafts (square threaded and smooth keywayed) from the gearbox along the frame front..?

As I mentioned I have never really understood how the various levers work in relation to each other.. I know one lever on the Apron (?) engages either the cross slide or carriage travel.. Well, 2 levers actually.. Whats it's history..? It would be helpful to learn.

I should find an evening class..

Thanks again

Regards

Martin

[Brian WoodParticipant @brianwood45127]

Hello Martin,

The two shafts along the front of the lathe each serve different needs. The threaded one is only used for screwcutting to preserve the accuracy of the 4 TPI pitch thread, the other plain shaft has a keyway cut down it's length and this drives a worm within the apron that provides either the powered cross feed or the powered traverse, but not both at once! There will be an apron control that selects those functions as required.

You will also find an effective interlock mechanism built into the apron that positively prevents the chance of selecting the power functions when screwcutting and visa versa.

It doesn't take a lot of imagination to appreciate the damage that could result with those potentially very different pitch controls being engaged at the same time

If you look at the splendid website lathes.co.uk and chose Denham from the list of lathes there is a wealth of information there to add to your knowledge and understanding of the model. Tony also sells good quality digitally remastered handbooks; I'm sure the Denham Junior will be listed and it would make a nice birthday present for you. I think that might be of more use than an evening class, even assuming you could find one with an appropriate syllabus

Regards Brian

Our apologies to Donald by the way for highjacking his thread

[Roger ClarkParticipant @rogerclark]

Hi Martin, send me a pm through the inbox at the top of the forum with your email address and I'll send you a pdf of the manual.

Regards

Roger

[Donald BlakleyParticipant @donaldblakley76520]

It's good to see people still talking about them. I have just had a new intermediate shaft made for mine. Hoping to rebuild the head stock in the near future.

[Martin ChamberlainParticipant @martinchamberlain57475]

Hello Brian,

Thanks again for improving my knowledge. I found a YT vid by Mathew Warburton only 1.17mins long showing a beautifully restored Mk 2 and he had it running and almost showed me everything I was hoping to learn.

Perhaps he is known on this Forum..? YouToob : Metal lathe Denham Mk 2 Junior

Roger.. PM sent. Thank you.

Donald.. I am pleased you have a new shaft.. and sorry for highjacking..oops

Signing off for tonite.

Thanks

Regards

Martin

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