Building a Lathe face/drive plate

[Brent H]

@YYCHobbyMachinist wins! Yep, that is the stuff. I have used the stuff from KBC tools in the big bottle at work. Works well if your prep is good.

 

[historicalarms]

In one of your post's you state "the plate is out from perfect flat by about .003".

In one of his books, Tubal Caine states that "every faceplate should have a very faint/small taper from outside to the center".
I have never figured that out...cant come up with a reason that a taper is preferable to a "super flat" mounting surface. The face plate that came with my lathe wasn't "true" to the lathes axis so I did take his advise & make a slight taper cut to the face to true it up....but still cant figure out why...

In an oddball shaped workpieces & clamping fixtures that do cause an off-balance situation that causes vibration...that vibration can be minimized by speed reduction rather than messing with a bunch of counter balancers to be clamped on.

 

[Hruul]

@YYCHobbyMachinist You are correct. I have both, the Brownell's was the one that came to mind first.

 

[RobinHood]

All three lathes I have state a maximum speed when running a face plate. E.g. for the SM 1340 it is 500 rpm max with a 12” plate. Colchester says you can go to 1400 rpm max.

The taper towards the center is the same idea as the cross slide: it should either cut perfectly at 90* to the axis, but since that is very difficult to maintain over the life of the lathe (because of wear), they are usually set to do facing cuts of a few tenths concave. Keith Rucker mentions that Monarch recommends about 0.0005” for his 16” machine.
This way, faced part will butt snuggly against each other when stacked. If the ends were convex, they would rock.

 

[Brent H]

Well HOT DAMN!! A perfect Mr Pete Plate! LOL!!
That was great luck - LOL - my plate at 9” would never be going faster than 500 RPM - the surface feet per minute at the outer edge would be 1177.5. That would be pretty quick. 300 worked well for its test.

I tried it out with the lathe dog on the plate and there is no perceptible vibration so that is good.
I am currently making a centre for the rotary table so I can get more gears cut. I will be posting that on another topic thingy. I am using a piece of the ship’s hull for one of the parts.

 

[YYCHM]

Hi @PeterT

So I measured the shank of the cutter and it was 0.400 so that is needed a bit more clearance (say 0.015”). Since I was cutting on the rotary table things were somewhat easy. Once the table was square and centred I determined where I wanted to stop (some folks might want to plow right through - saves time).
I cut in to what I wanted the depth to be, in my case was 0.610 for a 7/8” thick plate. Once the final pass was done with the 3/8 straight cutter, I simply made a pass 0.020 either side of centre leaving a 0.415 wide slot.

the floor of the T is set with the T slot cutter. I brought it in to just be touching bottom (say a couple thou) and it did the rest. Power fed it in and out and while feeding blew the chips out (comp air) to keep the cutter from jamming up on material. Also a bit of oil for side lube of the cutter. So no clean up pass just the feed out and keeping chips out of the way.
For blackening I used the gun blue stuff from Cabelas but - rinsed the parts in a bit of paint thinner to degrease and remove bluing, cleaned off and then soaked in an acid solution to remove any rust and mill scale - you can go harder with a diluted muriatic acid but outside and with huge ventilation. - I just soaked in vinegar for a few hours. Blew all clean and swished them in the bluing. Sit for 10 minutes in the bluing - then dry all off and coat in light oil - like spindle oil.

Once again you have lost me What are the overall dims of your T-NUTs?

I'm trying to decide what dims to slot my faceplate to. I'm thinking 8 slots relieved on the backside to accept 3/8-16 T-NUTS with a 7/16 slot which means I need 7/16 and 11/16 end mills.

Also, what is the preferred order of milling two overlaid slots? Narrow followed by wide or wide followed by narrow?

Thoughts?

Craig

 

[Brent H]

Hey Craig, if you are milling a slot within a slot , so to speak, I would mill the larger slot (larger cutter, stronger) and then switch to the smaller one and mill out the centre.

for mine I actually cut in T - slots (thicker plate) with a dedicated T slot cutter specific for 3/8” bolts (basically you can slide a 3/8” bolt into the slot)

 

[YYCHM]

Hey Craig, if you are milling a slot within a slot , so to speak, I would mill the larger slot (larger cutter, stronger) and then switch to the smaller one and mill out the centre.

for mine I actually cut in T - slots (thicker plate) with a dedicated T slot cutter specific for 3/8” bolts (basically you can slide a 3/8” bolt into the slot)

Your T-SLOTs accommodate 3/8" hex head bolts? What were the T-NUTs for?

 

[YotaBota]

I am using a piece of the ship’s hull for one of the parts.

I hope the piece was taken AWL!

 

[Brent H]

@yota - it would be a terrible sinking feeling if the ship was in the water when we cut out the bow thruster- LOL

@YYCHobbyMachinist :





The T - nuts give me the option to bolt from the front and the bolt head allows for using bolts and nuts, washers etc. The slot, however, mills wider than the bolt head so the head will spin - not a deal breaker - the 3/8 slot cutter takes some big cut as it does both sides of the slot at the same time.

you can recess the slot to fit a bolt head nicely and then it will hold from turning. Then use a nut on the back or front what ever you require.