Lathe build update: Cross and top slides

[Evan]

It took longer than I expected to get to this stage. In large part that was due to some machining procedures taking longer and also because I was sidetracked last weekend doing auto repairs.



The thick bottom plate is the actual carriage and is mild steel. All of the rest of the components above that are cast iron. Most of the parts were taken from a low cost import X-Y table. The overall quality of the table was dragged down mainly by lack of attention to detail such as proper fitting of the dovetail ways and crummy fit and finish otherwise. The cast iron however is first rate and well cast.

The cross slide has a travel of about 7 inches from the front to centerline but can continue to the back for a total of 10 inches travel. Swing over the cross slide table is a hair under 9 inches. The top slide has a travel of about six inches once I get proper lead screws mounted. Swing over the top slide table is about three inches. Because the tool holder can be set back on the table and because of the type of mounting base I used for the top slide it is basically a built in ball turning attachment that can do up to 3 inch balls.

[.RC.]

Nice work...

[macona]

Looks neat-o.

But its possessed! Look! Its moving by itself!

[Davek0974]

Looks neat-o.

But its possessed! Look! Its moving by itself!

It's what power feeds do when there's no one about

Nice work Evan

[Evan]

It will have power feeds for the long and cross feeds. I have them on my SB9 and I wouldn't be without them. It is probably the single most useful item that can be added to a manual lathe after the usual accessories. Note that the animation shows the possible location of the compound on the cross feed table, not where it may be located by moving the table. Also, the handles and dials shown are strictly temporary. Proper ones will be fitted.

[Peter.]

I like the cross-slide idea for plenty of adjustment. What's the machine weigh-in at now Evan?

[Evan]

I haven't yet weighed the assemblies but I would guess about 300 lbs. My goal as I stated previously is to have no single component weigh more than about 150 lbs. The bed will be the heaviest part once the various doubler plates and tie plates are installed. It may go over my limit but not by too much. The headstock includes the large baseplate which will unbolt from the bed with about eight bolts. The spindle cartridge can be easily removed from the headstock,

That reminds me, I figured out a way to restrain the tail end of the spindle cartridge that seems will both restrain it adequately and also deal with any resonances that may be present.



The indicated ring is fastened to the top of the main support with a fine thread grade 8 or better stud cut from a socket head cap screw. The ring is planed off to present a flat area of about 3 sq inches that meets the top of the support and is adjustable with shims. To control resonance the ring has a gap to the cartridge of several thou and inside are several highly compressed neoprene O-rings that maintain an equal gap all the way around so the ring does not make actual metal to metal contact with the barrel.

I will be interested to see how it works.

[John Stevenson]

Sorry but it still looks to be the weakest point of the design and probably the one point that the whole design hinges on - literally

.

[Evan]

That may be true and is easy enough to deal with if it proves so. I have a plan to diagnose vibration and chatter issues in a much more specific manner than usual by using my Audiolumitron to pinpoint what parts are vibrating and at what frequencies. In testing the ALT this summer I found it is sensitive and specific enough to detect the beating of the wings of an individual gnat which surprisingly beat their wings at a much slower rate than a mosquito.

Forces on the spindle will be at a maximum when turning close to the spindle. In that event the leverage is the least to transmit forces to the back end of the spindle. In usual turning setups as the tool forces are applied further from the spindle nose either less force is used or additional means of support are brought into play such as the tailstock and/or a center steady or follow rest.

I see I failed to mention that the stud that holds the ring is 1/2 inch diameter. My first approach if that is a weak point will be to increase that to 1 inch as that will greatly increase the rigidity of the connection to the support.

[John Stevenson]

It's not the size of the stud but more of the contact area the ring is sitting on.

You have obviously done a lot of research and gone a very long way to a purposeful build, as demonstrated by the current cross and top slides but looking at this from a different perspective it seems as if the headstock is an after though, not one of the basic building blocks to build the machine round.

I don't wish to appear derogatory but standing back and looking at the overall design this stands out in my eyes. I have no idea what others think but it's not up to your usual standard of build.

.

[Evan]

That remains to be seen John. I don't intend this machine be used to turn truck flywheels or similar. If it is a weak point I will report it since this is a much more likely candidate for others to build than my milling machine. So far I have about $2.00 invested from the current account for some O-rings. This is and was intended to be a light weight machine and will have limitations that correspond to that goal.

[Circlip]

The tee-slotted cross slide is excellent, surprised many more manufacturers didn't pick it up as Maier did on the Maximat, but, can you explain the advantage of using slots on the topslide?

Not picking, just a genuine interest.

Regards Ian.

[Your Old Dog]

In testing the ALT this summer I found it is sensitive and specific enough to detect the beating of the wings of an individual gnat which surprisingly beat their wings at a much slower rate than a mosquito.

Evan, it's time to get out of the shop for awhile. Go for a nice long ride in the country with the wife.

Nice build so far, will be fun to see if you can get the kind of accuracy from it that your mill seems to be producing.

[John Stevenson]

That remains to be seen John. I don't intend this machine be used to turn truck flywheels or similar. If it is a weak point I will report it since this is a much more likely candidate for others to build than my milling machine. So far I have about $2.00 invested from the current account for some O-rings. This is and was intended to be a light weight machine and will have limitations that correspond to that goal.

I accept this Evan as as you say it remains to be seen, I know you want it for a light lathe but if others build it will they also restrict it to being a light lathe. Not your problem I know but, and sorry to harp on about this , it looks an after thought.

Out of all your designs and builds this one stands out in my mind, the cartridge idea is fine, it's just the way it sits on the bracket like Humpty Dumpty.

Ian,
When I had my Myford ML7 I bought the long cross slide and screw for it. This than gave me the normal cross slide screw as a spare.
As the ML7 is limited on the taper it can cut as regards travels, it can do a MT2 but not a MT3 I decided to make a new topslide to use the longer screw.

As I had a clean sheet of paper I thought it would be a good idea to put T slots in it and so I did.
Looked nice, worked well but i never found a use for the tee slots

[Evan]

I don't know how useful the upper tee slots will be but I had a chunk of a small table and so used it. It will be useful for turning balls where the tool must be behind the center of rotation. The method I used to fix the top slide to the cross is the same as South Bend used on my SB9 except I increased the central plug size to 3 inches from 1.25". It makes an excellent bearing so the compound can be rotated while turning to cut concave and convex forms.

The support for the spindle is a piece cut from the base near 2 inches thick and is braced by the two solid stock angle brackets on the side which are welded to it. It won't be moving much regardless of load. If the cartridge isn't sufficiently well supported at the back a simple yoke fastened to the support ring and extending down either side of the main support plate will certainly secure it.