Fixing Darren's lathe

[John Stevenson]

John,

We are not talking about an artic full here, just a nice pile. By the time they have been shared out, maybe one or two each, for those special little jobs that HSS can't cope with.

Bogs

Just a wind up John, Anyway the Donald is still off the road, need to get it MOT'd

JS.

[bogstandard]

I realised that John, but knowing you, you would still just turn up for a free coffee.

Even though it would most probably cost you 30 squid in fuel for the round trip.

John

[Darren]

My problem is getting and staying in the shop for any length of time. I feel absolutely awful because I have taken so long on this project.

He John, don't be so silly, it takes what it takes.......besides it's not like I'm a dead duck without it.

Sure looking forward to seeing it again though, but then who wouldn't be 

Health is more important, you just make sure that comes first and take it easy...

[bogstandard]

THE FIX

After the fiasco on the last post, I have actually managed to get something done about it.

As you know, I keep all my little offcuts. Well this time they came in very handy. The bits I cut off the ends of the gibs were rough cut up and placed in the jibs to fill up the previously cut slots.




A quickie makeshift hearth, a bit of creamy mixed flux and a tiny bit of silver solder. Give it a bit of heat.




And you end up with two filled in slots. Not pretty, but they won't come apart. Ali bronze, from previous experience, is an absolute pig to silver solder. But by keeping the heat on a bit longer, I managed to get it to flow.




By using the accurate tapers to my advantage, I had no trouble holding the strips to dress down the excess filler blocks.
A few dressing cuts and it was difficult to see where the repair was done.




On this shot, by using my taper blocks, I set up my mini vice to hold the strips at the correct angle (45 degs) to cut the new angled slots. As before, I lit up the background to see when everything was spot on.




Slots cut, screws nearly finished by putting a slot in the end but the threads still need to be cut, and it is all starting to look promising.




This is the rough position for the new holes. The blocks were mounted up as before and the new holes drilled and tapped.




All bits now assembled and work a treat.




If luck is with me tomorrow, I will get it all assembled and tried out on the lathe. After that is proved, the redundant holes will be filled in and the mounting blocks will be dowel pinned.

Then if all is still OK, I will start on the final assembly and setting up of the lathe. Just got to work out where all the electric string goes, as Darren delivered it partly stripped.

Red to red, black to black, green, haven't a clue.


Bogs

[SPiN Racing]

Beautiful 

cant wait to see it together!

[Darren]

Hi John,

Looking good as always,
I was only telling my mate, of many many yrs, tonight how my little machine is being made into a Swiss watch by an ex Roller engineer.
All came about cos he was talking to a gentleman of the same ilk earlier today, sumut about cars or something .. 

Anyways, my reason for posting, from memory there's only 3 wires to connect? One goes inside the control box for the speed sensor, a bit fiddly but not too bad.

[Bernd]

Bravo John. Nice save.   

Usally green goes to "ground", but then in your case who knows it could be another colour that is ground.

Bernd

[bogstandard]

I was only joking lads, I have already got the wiring figured.

If it's hangin' loose, just stick it in the nearest open hole and forget about it.

Darren's problem then. 


John


BTW, don't be fooled by the R-R bit. The production line cars, by and large, fitted together nicely, the hand built ones didn't, that is why they had to be hand built.

Bodge it and Dodge it. Purely cosmetic.

[SPiN Racing]

OHH Minor Derail....

I told the owner of the shop that works on all the Rolls, and has the race shop side I work in..

He is a old school mechanic.. granted he is only mid 40s, but he worked with some very very very very very big names in the automotive workd here in the states. And actually a lot of the cars he ahs maintained go to the one really big show every year. I spose I will leave it at that. BUT... He works on a LOT of older hand built coachwork cars.
Things where everything... EVERYTHING is hand fitted. And makes castings for parts that cant be made anymore, and machines them up in the shop.

Sooooo Talking about that Rolls Carm.. something or other.. and the wonderful fit on the doors.. cough.

He wanted me to mention Italian Coachwork to you.. Figured you would fall over laughing about the fit and finish of it.

(Im clueless sadly.. never having owned any Italian cars)

[rleete]

Bodge it and Dodge it. Purely cosmetic.

I worked for a company a while back (Morrison-Knudsen) that refurbished subway cars.  These particular cars were for NYC (you've seen them in countless movies), and were known as R-44.  They were called that for rail, and being 44 ft. long.  The original shells were built in the late 1940's, and that company was no longer around.  Anyway, the nominal length of the cars was 44', but we discovered that they actually varied by up to 18" plus or minus!  Therefore, all the interior panels, equipment, etc. had to be designed such that it accomodated these variations.  The saying in the shop was, "hammer to fit, paint to match".

[bogstandard]

R,

"hammer to fit, paint to match".

That is spot on.

Every single moving panel on the Carmargue had to be 'tweaked to fit'. Doors were different lengths (anything up to about 2") not only between cars, but different sides of the same car. It would take a dozen of us, about 4 weeks to get all the panels, electrics and bumpers (fenders) corrected and fitted to a rolling chassis. Every little job had to be done by hand.

Spin,

Italian bodywork.

The Carmargue was actually designed by Pininfarina, a famous Italian design house.
http://en.wikipedia.org/wiki/Pininfarina#Notable_designs
The white line men had to use up to 1 cwt of lead on the body to get all the necessary sharp edges required to get it to design specs. In some areas the lead was over 1" thick, just to get the bodywork to line up and look right. Even the stainless window frames were tack welded up on each individual car in situ, to make sure they fitted correctly.

But after all that, they looked spectacular and drove perfectly when finished.

John

[John Hill]

There used to be a small vehicle assembly plant in our town and among the products they produced was a particular Ford ute (pickup) from Australia.  This was a true ute in that the body panels were welded to make one unit with the chassis etc.  They had an assembly jig from the Australian factory but it was distorted so that neither  the doors nor the bonnet (hood) could be made to fit.  Someone solved the problem by setting steel rings and chains in the floor, they would assemble the whole vehicle then roll it over these fittings, cinch her down then run hydraulic floor jacks under at the critical points.  By magic, everything closed perfectly!

[bogstandard]

Right, back to the job in hand and no  included.

Had a couple of hours in the shop, and as usual when I want to get on and finish the job, another problem rears it's ugly head.

So, I had fitted everything up for first trials and it was looking rather well. Unfortunately, as I was bringing the rear gib to height, it was tightening up, but not up and down, but side to side. After a quick stripdown I notice a small scrape mark on the paintwork. On further inspection, the problem bulge was also on the side of the casting, in the same area as the top one, and the same height, about 0.015" (0.4mm).

This time, it wasn't so bad, I just dropped it in the vice and wacked the material off.

As can be seen, the area that was removed proved that there was a bulge. It didn't matter on the operators side, as that area had already been machined by the factory, and wasn't causing a problem.



I was ready to try again, and the gibs were adjusted up.

Just one thing, Darren will never have to worry about a jumping saddle any more. It works perfectly, smooth as silk and free as a bird, with no hint of play anywhere. It will be even better when it is lubed up.

If I was to do it again, or if anyone is contemplating doing this, I would make the holding block and gib strip 0.025" (0.06mm) narrower, make the gib 0.275" wide instead of 0.300" and adjust the holder to suit. This would negate the casting problems I have come across.


Back on track Bogs

[HS93]

After all this work is it worth skimming the feet of the bed so it will be garanteed to be flat ??? just a thought

peter

[Bernd]

Lookin' good Bog's.

I was looking at the Grizzly today as I was turning the piece of aluminum for my tool holder and noticed how the whole saddle was jumping while it was taking a .05" cut. I got to thinking about what you've done to Darrens lathe. I think a total tear down is in order on this lathe.

But first I need to make some tooling.

Bernd

[bogstandard]

Peter,

When I did the first machining steps on the casting, I checked the bed to the feet, and it was spot on.

BTW, when this is done, I have one small private job to do, then I will be showing how to make a tramming tool (nudge, nudge, wink, wink, know what I mean).

Bernd,

The only way that the saddle can jump about is if the operators side gib is not set up correctly. If it is pulled down onto the prismatic shaped bed, it should not be able to wobble about. The back side gib acts to keep it from going up and down under cutting pressure.

Even my lathe has the same method of gib strips as this one used to have, so if it starts to play up, I will fit these type of tapered gibs to it. They really are very easy to adjust, and if made well, unbeatable in the way they operate.

John

[Bernd]

John,

I believe that the jumping is caused by the drive mechinism. It is a very poorly design drive.

The Grizzly doesn't have tapered gibs. This one has straight gibs.

From what I gather that you are saying I could fit taper gibs on the lathe?

Bernd

[bogstandard]

Bernd,

If it is the same gib style as Darren's, then sure, with a bit of measuring up, tapered gibs can be fitted.

All they do is basically sit in a block that mounts in the original gib position using the original mounting holes. I only machined up the saddle because it had not been machined up correctly in the first place.

BTW, 0.100" is a standard depth of cut in steel and up to 0.250" in ali or brass on my machine. Take no prisoners.

I am just doing a job now that goes from 1/2" down to 5/32". Two rough cuts and one final. I am making some spare adjusting bolts for Darren if ever they are needed.

Not actually for Darren, but his lathe. He's not yet bionic.

John

[bogstandard]

Rather than babbling on and spouting bulls**t, here is a little vid to keep you going.

If I feel up to it, tomorrow I will finish the lathe off and give it a run, to see if this mod has cured the crappy finish problems.


John

[SPiN Racing]

Ohhhh Verrry Nice!

I think its time to check my lathe and see how much slop it has.. and see if its adjustable.. or if I need to start planning for something along these lines LOL.

[Bernd]

Nice vid John.

That sure looks smooth. A lathe that can have the saddle moved like that without any real effort is a joy to have.

Darren I'm jealous. 

Bernd

[Divided he ad]

...... So when do I get my saddle booked in John        



I like the look of this.... And I'll get to inspect it in 2 days    Unless you have it back together and tested by then and Darren is there like a shot to take it away and start dirtying all it up!! 


I'll make sure I give it a thorough going over ..... So I can replicate it, between this post and the seeing it in person, I think when I'm feeling brave and foolhardy all at the same time I can have a go   


Nice vid, tells us all what we need to know.... Except the web address    ..... Maybe in the description? ..


 



Ralph.

[Brass_Machine]

Nice! Can't wait to see it in action. This I hope would fix the issue. Now all Darren needs to do is replace the headstock bearings (maybe?) I saw that mod on the interweb somewhere. Nice Job John! I may be inspired to do this mod come summer.

Eric

[bogstandard]

Thanks lads,

If the lathe casting hadn't been so bent, bulging and twisted, and knowing what I do now, this mod would have been a piece of cake.

The position of the adjusting screws work, but in hindsight, the correct position would be between the two. But it works, so job done. If it is cleaned and lubed up regularly, the gibs shouldn't need resetting for years, and as it is, once the machining marks are bedded in over use, it will only get better, still a mite tight.

Ralph, I put a new name on it. Might attract a few more twisted members. . But this post has already had a load of hits, and I don't think that is all from the collective having a look.

We will soon be hitting the magic 200.

I don't have the time or patience at the moment to embed a load of text or music, so just a quickie.


So now, every part of the lathe is going to be set up to perfection (well, so it works right), and we will then see if we have made a good precision lathe out of a cheapo Chinese lump.

John

[NickG]

Hi guys,

I can't view the video at .. erm .. on this computer  but it sounds like you've done a great job Bogs.

With taper roller bearings in the headstock it should be a great little machine.

Nick