Installing a Logan QCGB. Logan 9B to 400 adaptation.

[AR1911]

I'm confused. The bull gear is the largest diameter gear, right behind the chuck mount, to the right of the belt pulleys. It is only used for the back gears.
You seem to be referring to the long gear at the other end of the spindle which send power through the geartrain.

 

[AR1911]

OK, let me try this again while we are looking at the back of my apron:

Upside down, sorry. I corrected it, but it reverts when I upload

Dead center is the worm drive. The internal key picks up rotation from the lead screw which passes though it. It also passes through the half-nuts, but they remain open.
This spins the gear at the top of this photo. It freewheels unless you engage the clutch. Then it drives a gear behind the worm which in turn drives the BIG gear in the lower part of this photo.
That gear is on a lever attached to the selector lever on the front. It swings down (toward the clutch) to pick up a gear that drives the shaft at the left side of this photo, which turns against the rack for longitudinal feed.

Move the lever up and the gear moves up. In the above photo it is in the crossfeed position. You can see it sticks up above the top edge of the apron.
That big gear, when moved up via the feed lever, engages the gear on the crossfeed shaft, as seen in this photo of the carriage:



Hope that helps

 

[mjhenks]

Your confused. Believe me, i am the one who is confused. :whacky:

Stud gear. That is what i meant. I went back and corrected that.

I believe the gear in red is the Stud gear. If i have that wrong please correct me. This is the gear though that apears to be sticking out farther on the 9B machines.



Matthew

 

[AR1911]

Alignment of box to bed. I sent you this a few days ago via email. Note the overhang.



Here's what my stud gear looked like:

 

[mjhenks]

Rex,

Did not receive that first picture.

I see there is quite the overhang of the box to the bed. That picture is alot clearer than the dirty lathe picture i had. The overhang along with the added length to the stud gear shaft would make alot of sense as far as why the box overhangs.

Can i get some details on your stud gear shaft?
What does it look like as i think i need to make one.
What is the overhang of your box beyond the bed.

Another issue that this may solve is that the right side of the box hits the longitudinal rack.



I will cover this little discovery more later.

Matthew

 

[mjhenks]

Rex,

Understand the apron now. The longitudinal motion is driving the hand wheel which is using the rack to move the saddle, not the lead screw. That saves the half nut from needless use. Got it.

How about forward & reverse? Is it just one way on this model? In and to the left?

I was playing with the power cross feed today on a larger lathe. Facing off a nasty cast iron back plate to make into a usable piece. (Thank you Henry BTW) The power cross did make it nice and gave a nice finish despite the cast iron.

Matthew

 

[AR1911]

How about forward & reverse? Is it just one way on this model? In and to the left?

That lever that the stud gear is mounted on?
That reverses the leadscrew rotation, and thus changes the feed direction

 

[mjhenks]

That make sense. Can you change that gear while the machine is running? That would seam dangerous for the gears.

Matthew

 

[AR1911]

Nope, gotta stop the spindle. On mine you have to loosen a bolt to move the lever.

 

[mjhenks]

Next i looked at the drive shaft end support. Could i use the stock 9B-17 lead screw and the 400 shaft support?

Mind you that what you see below is with the gear box mounted .100" inboard from the end of the bed. In previous posts you will note that i do not think this is the right position for the box. Any change in the box location will affect the end support.

I installed the axial collar on the lead screw in its original position for the 9B-17 using the witness marks left on the shaft from the collar set screw. I then placed the lead screw into the box with the collar against the box. I then installed the end support as shown.



The lead screw JUST makes it. That is the bolts in the bed are usable but the lead screw is butted right up against the left side of the support. You can also see alot of extra shaft out the right side of the support.

This supports my previous thought that the gear box needs to move to the left once i figure out the stud gear situation. It also further supports that the 9B is a very close cousin of the 400.

No pictures but while fitting the lead screw into the end support i noticed a nice wear groove on that end of the shaft. I think i will be OK though as the groove is about 1/2" wide and the support is about 1-1/2" long. Plenty of support.

My conclusion is that the lead screw and end support are usable as is once i figure out the right spot for the box. (Assuming the box is moving to the left)

Matthew