Cx709 lathe

[PeterT]

I don't understand. Are we looking at your spindle in the last pic? The CX709 specs mention of MT5 nose & 1.5" ID bore. But is it a D1-4 mount & those are the 'holes' you are talking about or is there some other adapter plate involved?

Worded another way - its a LOT easier to get the right adapter plate to marry a chuck to whatever your spindle standard is then disassembling the spindle & trying to modify it. Especially a 'D' camlock if that's what you have. If its an integrated chuck meaning no possibility of modifying the attachment end to that particular spindle, then consider getting the right chuck.

Sorry maybe I don't have a clear understanding of what you are showing us.

 

[Bofobo]

This machine does not come with the mt5 dead center as advertised, but the spindle bore of 1.5" is behind the supposed mt5 taper and is a part of the "mounting plate" so to clarify. the "face plate" is the "mounting plate" and the pre drilled holes are the same as the 3jaw shown in other photos, it is matched, but the 4jaw shown has a larger bolt hole circle than the mounting/face plate.

Adding a backing plate is i suppose another option, but i prefer to eliminate variables since the shoulder on the 4jaw does match the mounting plate.

 

[Bofobo]

 

[PeterT]

OK, that's different than I expected. Bear with me. Can part A be removed with what looks like black capscrew? (what I will loosely call adapter plate). And does that leave exposed part B (what I'll loosely call spindle nose).

 

[Bofobo]

The socket cap screw a (x4) is visible only through a hole in the plate and does remove coller b

 

[PeterT]

ok, can you unscrew adapter plate A and buy/make a replacement plate for your chuck? That's exactly what semi-machined adapter plates do, they fit the spindle nose MT5 in your case, then you turn them in-situ to whatever back plate diameter/step is required to marry the chuck. The MT taper is to establish repeat concentricity.

 

[Janger]

Now I wonder if the BB lathe I owned actually would mount the 4 jaw. I never tried it and sold the mill with the 4jaw still in the box. Unfortunately you’ve got a QC problem to deal with. What is B.B. saying? They should replace a chuck and or the face plate or both...

 

[Bofobo]

Ive not been back yet

 

[Janger]

I can give you a slice of 4140 6 7/8 diameter mike if that would help with making a plate.

 

[PeterT]

Still trying to decipher your spindle. This link may or may not be similar to what you have. Seems like some BusyBee lathes may or may not have this spindle features like this. Read particularly posts #11 & #14. Does this look like your spindle? (I mean with adapter plate removed).
http://bbs.homeshopmachinist.net/threads/50047-Busy-Bee-Craftex-Lathe/page2

Here is the spindle dimensions they reference. See how you can have a #5 taper spindle nose, but many different mounting variations over & above that (holes/studs/camlock/threads etc.) at different spacings.
http://www.lathes.co.uk/latheparts/page11.html

I'm just guessing here based on interpreting your pics & comments but I think once you figure out what 'standard' your spindle is, you just need a semi machined adapter plate that mounts to the nose & turn it to suite whatever chuck you want to mate. Hopefully BB sells this as a part, typically they are CI. Next option if this doesn't pan out (and assuming you have a #5 nose, yes you can chuck up a nice slab of stock, but you need a real accurate tapered center bore to match the nose angle. On semi machined back plates, this is usually done for you, or at least quite close.

 

[RobinHood]

So to sum up: your spindle has a MT5 internal taper. It is the “back plate” for both your 3-jaw and your 4-jaw chucks. The 3-jaw chuck uses three mounting bolts on bolt circle diameter X. The 4-jaw uses four mounting bolts on bolt circle diameter Y. They both share the same register shoulder. By your measurements, bolt circle diameter Y is off by ~1/8” from where it needs to be in order to mount the 4-jaw chuck.

What size bolts are used to mount the 4-jaw to the spindle? Looks like about an M10 from the pics. Are they expecting you to use the same fasteners on either chuck?

As a temporary measure (until the seller gives you a satisfactory solution) you may be able to turn down the shank of four bolts that fit the 4-jaw threads. Give then nice radii where you neck them down to reduce stress risers. Insert the reduced shank bolts through the four existing holes in the spindle and draw the chuck onto the register. That should be plenty strong if you use high grade bolts. The forces are on the register shoulder and I believe you said that you have a good fit there.

If you consider a 3/8 grade 8 bolt (~M10) the clamping force of three of them holding your 3-jaw chuck onto the spindle would be about 3*6974 lbs = 20922 lbs max.
Now take the same 3/8 bolt and turn the shank down to 5/16 (~M8) and use four of them on your 4-jaw, it would be held on with a force of about 18876 lbs max. (4*4719 lbs). That’s within 10% of the 3-jaw force.

At least this way you could use your 4-jaw right away while you work with BB on a solution.

 

[kevin.decelles]

@Janger I'll be unboxing my 4 jaw from modern tool and doing a test fit based on this thread

Better now then in a year from now


Sent from my iPhone using Tapatalk

 

[Bofobo]

Thanks john, Oh! And i can return both pairs of your safety glasses . im going to make the trip some time im the next week to busy bee to see what they say. And start looking at the parts blow up. The lathe spindle is item 85 on the second image and is green on the first

this appears to show a one piece spindle with the backing plate, mt5 taper, and 1.5" thru hole as one, i will need access to a larger machine to make new holes, one reason i am steering away from an adapter plate is the loss of work space, its not a long bed and i already loose more space than i like with my poor choice of tail stock adapter for my drill chuck, new holes just seem so much cleaner albeit more work

 

[PeterT]

...green on the first this appears to show a one piece spindle with the backing plate, mt5 taper, and 1.5" thru hole as one, i will need access to a larger machine to make new holes, one reason i am steering away from an adapter plate is the loss of work space

'new holes' .... this is where I'm still confused.

- If you are saying new holes in a new adapter plate, that would be a mill or drill press work because the holes are perpendicular to the plate. You cant do that in a lathe. The plate OD/face/shoulder turning itself is done in-situ in the lathe starting with a semi machined blank. That guarantees that it is 100% concentric with your spindle. You mount the semi-machined blank on the spindle & turn it to whatever the (typically plain back) chuck dimensions requires. Then do the drilling.

- if you are talking about pulling the spindle & drilling new holes on the spindle nose section (yellow hilite)... well that's a different journey. Not only have you permanently altered a lathe that was set up to a specific standard, but you get to re-assemble all those bearings & re-establish the backlash fits etc. (pink shade).

This might not be obvious but when you buy a chuck, be it 3-jaw, 4-jaw, 5C collet...
A) it can be an 'integrated' style, which means the back end is already completed to be directly mounted to a specific standard spindle nose. Maybe its a screw-on, or maybe D1-4, or maybe German ISO... there are probably 20 different standards out there depending on the machine. There is no changing these, they can only mount to that standard. Some prefer integrated because they are a bit more compact & they don't have a need to ever use it on a different spindle.

B) The chuck body itself could be essentially the same as A) but its already pre-married to a removable adapter plate made to one of these spindle nose standards. If you take the adapter plate off, you are left with something like a plain back chuck that can be mounted to any another machine, providing to have the correct adapter plate which marries the 2 together. From what I can tell, this is your status - a chuck that needs a different plate to marry to your particular spindle. So I'm not suggesting 2 stacked adapter plates here, only one should be used but the 'correct' plate suited to your lathe. If that was properly packaged with your lathe, we probably wouldn't be having this discussion

Hope this helps

 

[PeterT]

example adapter plates
https://www.carbideanddiamondtooling.com/lathe.chuck.backplate.universal.bison.bial

 

[Janger]

@Janger I'll be unboxing my 4 jaw from modern tool and doing a test fit based on this thread

Better now then in a year from now


Sent from my iPhone using Tapatalk

Mine is ok I was using it. It did not come with the mounting cam bolts. I had to use the ones for the 3jaw. Try the face plate too.