Denham Junior Mk2 lathe

[yorkie_chris]

Hey up folks. First post on here, I've bought a Denham lathe and am after a bit of guidance with it.

This is the feller as I saw it on eBay


Cleaned it up a bit




Need to sort a few bits with it, for a start the reverse on the leadscrew and power shaft drive is missing


Also the compound slide is damaged so I may need to swap that for one from another lathe as I don't think it's repairable (pics to follow). And, I need more changewheels at some point, not to mention some idea of how to use it! 

Cheers!
Chris

[yorkie_chris]

Detail of damage to compound slide.

I don't think this can be repaired easily due to the damage to the T slot as well as the slide itself.


This is the top slide, I hope to find a compound slide assembly from another lathe that will fit easily on here if I cannot find a Denham replacement.


In other news, it grinds a bit, especially at higher speeds or when under a load.
I thought it was the gears so had a look in the headstock.


It was worse in top gear of the 2 final reduction gears, these:


But they look fine, so I got looking a bit further and now I think it is this bearing which has seized and makes the input shaft harder to turn than the other two (even with no belts/motor on there).




Next job, replace the bearings.

Has anyone got any idea what this shaft would be used for?

[BillTodd]

Has anyone got any idea what this shaft would be used for?

At a guess, a relieving attachment (for producing the back clearance on a milling cutter etc.)  or perhaps some live tooling (e.g.thread milling head)

Pity about the top-slide, doesn't look repairable to me. I think I'd try and find a small slide from a myford or boxford and then make an adapter plate. The rest of the lathe doesn't look too bad (is that scraping visible on the ways?), lead-screw looks OK (not done much treading) .

Have you got the filler section for the gap bed? [edit] yes i can see it 

Bill

[yorkie_chris]

Yes you can still see frosting on a lot of the bed 

Got the gap piece, but it needs the rust taking off it. And I need a supply of bolts in ignorance sizes as all my stuff from working on motorbikes is metric.

[Rob.Wilson]

Looks a good solid lathe Chris  

In allot better condition than my CUB lathe 

Have you had a look here  http://www.lathes.co.uk/denham/


Rob

[yorkie_chris]

Yes, seen that site. Lots of useful info, I can't seem to find any spares sources yet though.

A friend got some dimensions of his harrison L5 for me, seems the holes in the compound base of that would near enough match up with the T slot in my topslide to fit. So that's the plan B if I can't find anything to drop straight on.

[Jonny]

Bed slides looks similar to a Harrison 9, 11 and 140.
If you have a miller dare say you could make a better one.

Went in to buy one of those CUB's 11 years ago D1-5 odd ball  What a reprieve.
Have the real thing now they tried to copy.

[yorkie_chris]

Sadly I don't have a miller, "my first machine tool"  


So, today I went to global surplus and bought:


A whacking great compound slide and 4-position toolpost  

Here's the top of my cross-slide and 2 views of the base of the compound slide I just bought.


That isn't going to fit. The studs don't line up with the holes (near enough that a bit of persuasion will get them in) and the central fixing is all wrong.

I reckon if that is milled flat, and the 0.5" hole sunk into the middle of it to match the spigot, and thinned down a bit while we're there to get the clearance right, it should do the trick nicely.

[yorkie_chris]

[yorkie_chris]

Well I fitted slide, looks very similar to one on a herbert pre op lathe actually, but still, who knows what it is...

Anyway, it's landed with about 9mm of clearance between center and bottom of toolpost, so that will need to get whittled down a bit to give me a decent amount of clearance.

[yorkie_chris]

So I moved it about a bit, stuck the drip tray on, got the base to within ballpark of level and bolted it down with some chunky throughbolts



Then faced the raised part from that new compound slide base, drilled it and reamed it .500" on same center and it drops straight on. Just need to open the holes up a bit to line the T slots up and it should be more rigid than new


Only problem with it, I only have about 9mm of clearance from toolpost to center, so will need to machine the toolholder down a bit.


Next bit, making a motor mount

[andyf]

Great improvisation with the slide, Chris 

You could always make do with 8mm tooling until you get a QCTP.

Andy.

[Stilldrillin]

Way to go Chris! 

Adaptability....... 

David D

[yorkie_chris]

Great improvisation with the slide, Chris 

You could always make do with 8mm tooling until you get a QCTP.

Andy.

Cannae be wastin tha brass now lad!
Got some unistrut for the motor mount for my second favourite price of all as well; Free! 

Yeah that might be an option until I can machine this fella down, I've got a line on some cheap carbide stuff, but it is in fairly large sizes so I will need to trim it down at some point.

[Pete.]

Nice job Chris.

I made an insert tool holder for my dad's lathe using a small block of cast iron. I just machined the corner to accept the insert, made a hole to mount the block as a toolpost them set the center height by machining the base to suit. Jackary had a good idea with his stepperhead cnc lathe where he used a triangle block of steel and machined the three corners for three different insert types. Changing the toolpost would be quicker than changing a tool in the 4-way and the center height would always be perfect.

[yorkie_chris]

tonights bit, start lashing a motor mount together

[yorkie_chris]

Nearly ready to make some swarf 

[yorkie_chris]

 

We have swarf!

[Stilldrillin]

Yay! 

What cher made? 

David D

[yorkie_chris]

Yay! 

What cher made? 

David D

A mess!

Tried to cut a bit of a test bar, but it's come to 8 thou of difference in diameter over about a foot of length.
However, no tailstock support by necessity for that test to mean anything and probably not an ideal tool for it... so in all likelihood meaningless.

However... SWARF! 

[yorkie_chris]

Oh bollox!

Just realised the missing carriage reverse gears have fixed me to the carriage moving RIGHT* (without a load of buggering about with the changewheels to reverse that) which if I'm not mistaken is going to limit me to left-handed threads.

D'oh.


*Edited as I'm an idiot

[Stilldrillin]

Oh bollox!

Just realised the missing carriage reverse gears have fixed me to the carriage moving left (without a load of buggering about with the changewheels to reverse that) which if I'm not mistaken is going to limit me to left-handed threads.

D'oh.

That will be handy..... Occasionally! 

David D

[andyf]

Oh bollox!
Just realised the missing carriage reverse gears have fixed me to the carriage moving left (without a load of buggering about with the changewheels to reverse that) which if I'm not mistaken is going to limit me to left-handed threads.

D'oh.

  The carriage going left towards the headstock under power is normal for RH threading, isn't it? Or am I missing something?

Andy

[yorkie_chris]

I'm half asleep, the carriage will move RIGHT, away from headstock
(edited)

[yorkie_chris]

I can't figure out how the reverse was meant to work. Help!


this is the gearbox

Starting from bottom right going anti clockwise
First is the input gear driven by the changewheel
Above that is a gear keyed to the top shaft, it looks like it or some other gear on that shaft #should# be free to slide.
Left of those are the 3 gears also keyed to the shaft which give the A B and C feed speeds.
Below those are their counterparts, which are keyed to the lower shaft, the lower shaft goes through to the other side of the casting and the drive can either go to the power feed shaft or the leadscrew.
To the right of the 3 gears is a free area of shaft, it has a through hole in it, and a small drilling about 1/8" deep.

[Chuck in E. TN]

Check out this site.

http://www.lathes.co.uk/denham/index.html

Has info on this lathe. May have a manual.

Chuck in E. TN

[yorkie_chris]

He has a manual and parts diagram for £25, but no spares.
Will order a manual.

However would still like to figure it out

Here is a close up of the workings of the reversing lever, it moves between 2 detents 180* apart

I presume the hole is meant to hold some sort of selector fork

[yorkie_chris]

right reckon I've got it fathomed with a bit of help from a mate on another forum who is wise in the ways of science, well center distances and DP's anyway.

The input shaft should drive the 20t gear as it does now.

When you flick it into reverse the top 20t gear should disengage, but having a 30t gear attached to the left side of it, should engage another 30t gear on the bottom shaft which is driven by it's own 20t gear attached.

Clear as mud.

[Pete.]

I think the wide top gear on the right is a sliding gear.

On the shaft below it there should be a pair of gears connected together and free to rotate on the shaft, permanently engaged with the input gear on the lower right. The drilled hole is for a collar to keep this idler in place on the shaft. As you slide the wide gear left and right, it either engages directly with the input gear to the right or with the reversing idler to the left.

The three close-ganged gears on the lower left are the sliding gears for the three speed selector.

[yorkie_chris]

I see what you mean, but I don't think that could work:

That wide sliding one is a 20t, to mesh with one on the shaft below the one below it, the lower one would have to be bigger. The input shaft is on centers with the lower shaft for another 20t, so reversing it would change ratios.

So, I think a 30t pair are needed as the upper and lower shaft are on wider centers than the input to upper/lower distance.

Er, I think. I'm going to get another colchester bantam 30t changewheel the morra so I'll hopefully get it squared away.

[Pete.]

It would work if the missing paired gear were 16 and 25 teeth, 16 to permanently engage with the input gear and 25 to engage with the sliding gear. When engaged this would give a reduction of 5:4 (20:16) then an increase of 4:5 (20:25) keeping the forward and reverse ratios the same which is essential for screwcutting.

[yorkie_chris]

Centers of the 2 shafts are something like 1.875" so with 16DP that would be 30:30 wouldn't it? I bloody hope so because that pair of 30s cost me £20!

If all the pairs have same teeth then ratio is the same without needing to go up then down again.

i.e forward 20:20  1:1
reverse 20:20 (20 welded to the 30) 30:30 is still 1:1

Anyway we see if it works or not. I've got one minor cockup to sort in that there's a keyway in the shaft that the gears must slide past to assemble the 'box and I can't get the key out. (for the idler gears which are/will be free spinning on the lower shaft)

[krv3000]

HI well i hope you have lots of fun with that lathe

[yorkie_chris]

 

It works!
Betcha didn't see that coming!

Now to sort out some tooling.

[Stilldrillin]

It works!
Betcha didn't see that coming!

Now to sort out some tooling.

Don't talk daft, lad..... Of course we saw it coming!  

This is MadModder, you know!  



Blummin well done Chris........    

David D