Building a tailstock for a 12” Rotary table

[Brent H]

So this one is needed so I can support the mandrels better when making gears. I have some cutting to do on a longer shaft so this project is a must.
This is a small one for a 4” rotary table:


I you could just add some water and it would expand - that would be sweet! But no .....
The parts are coming from a heavy piece of angle I torched up and the centre holder part is from a piece of the hull (bow section) of the ship I work on. We installed a new bow thruster in 2016 so this chunk has been in the “future plans” section for a while - LOL. It is Grade E steel which means it is supposed to retain its properties down to -40° C. Ice breaking -LOL


Here is the pile of other steel:


Here are the very rough plans - still jigging them a bit:


And the base:

I got a good start on it today - will post more after I make the dinner ......

 

[Tom Kitta]

I almost build what you are planning to build - then I realized that I can use simply re-use an existing tailstock I had for a indexing head. Note that this is not the only design you can copy. It is probably one of the easier (but not easiest) designs through. I ended up making from the parts a wheel balancing fixture - i.e. static balancer.

Easier design would be one without adjustment up or down as an example.

Note that this will not really support mandrels well while cutting gears - what I used was a machinist jack right under the area being cut - unless the shaft you are cutting is really thick.

 

[Brent H]

The shaft is 1-1/4” plus a few other things to machine.

I mounted and centred the big block in the four jaw and then proceeded to drill it out to size. The hole is to be 3/4” so I drilled up in steps - 2 of the few #2MT bits missing in my set is the 23/32 and the 47/64th so I hade to change things up and bore the last few thou and then reamed to 3/4.



The. It was back to the mill for all the holes and threads.

1/16 slot cut to allow tightening up the centre


Holes for the set screw that keeps the centre from spinning when advancing it and the counter bore for the 5/16 socket head cap screw that locks the centre


drilling out the holes for the 1/2” bolts that will hold everything in place.

Milling out the bottom relief (3/4” end mill)



above pic is the back of the block. This will house the adjustment to dial in and out the centre - the centre is a piece of 3/4” round stock (pretty hard so like a 4130). The centre is drilled out to 2.5” and tapped to 7/16-20


That’s where I am today. Will be making a few brass items and the base part as soon as possible.

 

[PeterT]

You are a speedy builder, Brent.
When you do slitting/sawing like that, do you cut in progressively deeper passes, or one shot & just adjust the feed accordingly?

 

[Brent H]

I just let’er rip @PeterT - full depth and feed to avoid vibration, squeaks and other noises. As I have no power y axis it is hand driven - watch the chips and the heat - I try feed so it sounds like a clean cut and chips come out not burnt - cutter was HSS - applied oil as the slice progressed.

 

[DavidR8]

Wow! Fantastic progress Brent!

 

[YYCHM]

What dia slitting saw and what RPM?

 

[Brent H]

Slitting saw was 3” diameter, 1 inch bore, 36 tooth HSS at 95 RPM and feed rate as per me. I would think it took me 5 minutes to slice 2-1/5” ...... maybe 8 minutes. Added lube to start - my lathe takes 30W detergent free so I have several oil cans loaded with that as .... well you can squirt different places in the lathe so that is my lube ....

 

[Brent H]

Some lathe work today. Turned a 9/16” piece of 4140 down to 7/16 (0.4375) and then threaded it to 20 TPI. About 3” worth of thread for the adjustable centre.


Also made up a brass knob end for the screw. This fits the block and allows you to turn the centre in and out. The brass is 1” round stock and I shrunk fit the larger knob on (0.002” interference fit). Knurled the knob with a straight type knurling tool. Will have to work on that technique as it is a load on a little lathe.


I machined a 1/4” wide by 0.125” deep slot in the centre to allow it to go in and out. So this is the centre assembly:


Here is a mock up of the base - still need all the machining.

Burgers and beer now

 

[Brent H]

Ahh the saga continues.....

I missed a bunch of stuff as I was taking pictures and measuring for @YotaBota for the taper attachment on the Utilathe - anyway I surfaced the plates I needed to using a fly cutter - the first go was with a high speed steel cutter but I switched out to a carbide tipped cutter and it made for a nicer finish.

That pic is with the high speed steel cutter the fly cutter had in it.
Yellow arrow is the carbide and the red is the high speed steel.

Feeds and speed being about the same 600 RPM 10 to 20 thou depth of cut and reasonably quick speed over the part.

time warped and I just went at it so pictures are of it just needing some clean up


And then got welding ......




tomorrow may be some paint for the base and sides

 

[DavidR8]

Nice work Brent... how did you weld between the two uprights???

 

[Brent H]

@David_R8 - I have a large 250 amp torch and a smaller 150 amp one. The smaller one allowed me to weld just from about 1/2 way on either side.

when I started the welding I was going fast and was distracted a bit by helping my son change his winter tires - totally gapped that I had a roll of stainless in the machine - Argh!! Was absolutely sh...tie to start and things did not look nice. Had to grind off the tacks carefully and then change out wire.

to help keep things straight I cut a 1/16” deep pocket that the side fit into so they maintained proper alignment and spacing. I did have some shrinkage as things cooled so I skimmed the centre holder for a better fit. It is snug but moves about reasonably well.

 

[YotaBota]

I missed a bunch of stuff as I was taking pictures and measuring for @YotaBota for the taper attachment on the Utilathe

Sure,,,,,,, blame the old guy half way across the country,,, lol.
Looks good though. What is the relief reliefing around?

 

[Brent H]

Hey @YotaBota I posted plans for the Utilathe taper attachment - will be an epic project should you so choose - To which relief are you referring too?

 

[YotaBota]

To which relief are you referring too?

The one under the center, you used a 3/4" em.

 

[Brent H]

@YotaBota - I think you are referring to the bolt slots for holding the whole thing down to the mill table. Those are 9/16” for 1/2” hold downs and are 1.282” long.

 

[Brent H]

@YotaBota - that relief is to take out some of the steel so the Allen screw can clamp the centre in position easier. Adds some decoration as well. I can grab a few more pics tomorrow. The base is painted and drying.

 

[YotaBota]

that relief is to take out some of the steel so the Allen screw can clamp the centre in position easier.

Sounds good.

 

[Brent H]

Here are some additional pics - you will note the relief in the bottom the drill did not go straight - it was a cheap bit and wandered on the way through. Went fine on top

 

[RobinHood]

Looks really nice @Brent H, well done.

I think the reason for the drill to wander off center was because it was in an interrupted cut - not so much because it was “cheap”.

Two ways to mitigate:

a) drill first, cut slot into the drilled hole second
b) insert a piece of sacrificial metal of the same type in the slot and clamp it. Then drill.

Both ways, the drill no longer has an interrupted cut.

I guess a third way would be to use a long enough, center cutting end mill; it would not care so much about the slot (interrupted cut) and probably go straight through.