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

[mjhenks]

I have always avoided the change gears on my lathe. It is just a pain to do for a lathe that really does not get alot of use but is very useful when i need it. I have always wanted to install a QCGB on it. This is my thread to do so.

The game plan is:

- Research, research, research.
I have yet to find this conversion done but i have read a few items in adapting QCGB's to larger Logans.
- Locate a suitable gearbox.
From a 9B if possible but rumor has it that the 10" and 11" Logan's are the same.
- Figure out what, if anything needs to change or be added for the adaptation.
I do not expect it to just bolt up.
- Get-er-done.

I have owned my Logan 400 for about 20 years. (The logan 400 is a 9", short bed lathe. It is VERY similar to the Logan 1400 and 9B) It was made in the late 40's. My Grandfather bought it in the 50's or 60's from a VW shop that used it to turn brake drums. It was passed down to me.

Over the last 6 weeks i have undertaken a full restoration of the lathe once i found that the headstock bearings were shot. That project can be seen here.

http://www.hobby-machinist.com/showthread.php?t=20631

The restoration is not yet complete but i am too the point where i am slowing down as i wait for the last few bits to arrive.

In all honesty, i am already nearly complete with the first step and i have already located and secured the a QCGB from a 9B. However, for posterity and to help the next guy who wants to do this i will step thru each part with what i have learned and done. I believe this thread would also be helpful for anyone with a larger or different model Logan who wants to do the same.

Matthew

 

[Redlineman]

 

[mjhenks]

So like any good Engineer I started with research. Honestly I thought I would find a tutorial out there all ready. I know at the very least I would have to drill mount holes but i did not think it would be hard and others would have paved the way. I did the basic Google search on Logan QCGB finding some info but nothing that showed the adaptation. Many asking the same questions I was with the typical answer being "Don't try it unless you are ready to modify things". I was on my own.

So, lets start at home.

www.lathe.com is the home of Logan Actuator which is Scott Logan company. I am not sure the connection that Scott is to the Logan of 80 years ago but he has the same name and he is VERY helpful and quick at answering questions in regards to old Logan's. He also has spare parts for sale as well as a pretty active Yahoo group which he supports.
(https://groups.yahoo.com/neo/groups/lathe-list/info)

This link directly asks Scott if the adaptation can be done. Scott talks about the things that are the same and different covering the 9, 10 & 11" lathes. My take away was that the 9" or 10" units were possible source for my 400 conversion but that the drive shaft would have to be adapted.
http://lathe.com/ll-group-archive/adapting_a_qc_gearbox.html.

Parts list to see what was the same and what was different.
http://www.lathe.com/gearbox.htm


Searching the Yahoo group as well as forums like www.hobby-machinist.com and www.practicalmachinist.com and www.lathes.co.uk/logan further educated me on the parts involved but still no tutorial or clear path.

I always go to Ebay to find out what parts turn as well as general prices. It is amazing what you can learn on Ebay as well as what you can spend. How about a 3rd party option from "New All Western Aircraft" QCGB. Aftermarket parts. Cool. More info on this option can be found here. http://www.lathes.co.uk/westernaircraft/ They had units for Logan, Atlas & South Bend. What the actual difference between them I could not figure out. $90 new. Sign me up.


When all said and done I figured I was looking for a 9" or 10" box. Ideally with little wear and including the drive shaft & input gears. I figure I would have to adapt the drive shaft so that was not as important as the condition of the box and its parts. I also expected to have to fully rebuilt it. Cosmetics were not the concern but it needed to be complete. I should note that the 9" model that had the QCGB was the 9B. The 10" I believe was the 200 but I am not certain there.

Looking at the historical price on Ebay told me I should pay from $200 to $350 for a complete unit and of course 2 or 3 sold "last week" but I would not see another for 4-5 weeks.

In the words of Yoda, "Patience you must learn"

Matthew

 

[Redlineman]

Hey Matt;

I believe Mr. Scott Logan is the grandson of the lathe company founder. That's what sticks in my head anyway from reading lots of stuff. The 800 series lathes were built fairly early on in the life of the company, eventually concurrent with the 200s, and seemingly almost identical with the exception of the QCGB and lead screw. Is lead screw what you refer to as drive shaft? Anyway, I think the 820 model is the one I am looking for here, being essentially a 200 with the QCGB. Quite a few poeple have done the conversion, as you have no doubt read about. AFAIK you need a box, holes in the bed to mount it, and a lead screw, but that is to convert a 200. I don't know about a 400. Likely a bit more. You'll soon know far more than I on the subject, if you don't already. That is not hard!

 

[mjhenks]

Redlineman.

Certainly my research is more focused on the 9" lathes. You are right in that i found quite a bit more on the larger lathes. Thank you also for the info on Scott. It is awesome that he still supports us.

As this thread goes on, anyone who has additional information please feel free to add it.

As i go on, most of my info is going to focus on the 9" or 10" units. As the lathes get bigger i think the QCGB changes alot.

Here are some of the better pictures i have gathered in the spirit of research. Some of these are harvested from the net so if it is yours and you do not want it posted please let me know and i will remove it.

These are a few general pictures of QCGB on machines.



These are comparison shots of a 9B box next to a modern Powermatic box. Very similar in size and layout giving hope. (This is an 11" lathe)



Details of the 9" parts. This is the drive shaft end. (Lead screw) I am convinced that i can take a 400 lead screw and turn the end to match this and re-cut the woodruff key. The 400 does not need the key slot as it does not have power cross feed. If you are adapting an powered apron in your own project then you would need the slot. I think milling that would not be too hard either.

Some Dim's from a 9B-28
Tip of lead screw to first thread is 8.04"
Overall Length 39.75?
Right end of lead screw to gear box right side shaft bushing (collar) 37.375"



9B box dimensions. Thank you Rex B for taking these as well as other pictures for me.



Looking for 400 specific information to understand what will and wont fit. The colored arrows are specific info i was looking for.



Length of box: 6.5" (Yellow)
Height from base to top of bed: 8-15/32 to top of "V". (Purple)
Lead Screw to bottom of bed where QCGB mounts: ~2" (red)
The blue dim is lead screw from the bed. Have not pinned that down yet but am darn sure it is the same for all 9" & 10" units.


Matthew

 

[mjhenks]

So i am convinced that any 9" or 10" will work. I am pretty sure the 11" as well but have less evidence to back that up. If i were looking at an 11" box i would want the seller to take the measurements from my last post.

The search for a proper box took about 5 weeks. Of course there were a number of them that sold prior to me looking but as usual when you want it you cannot find it. I resisted buying one with missing parts because the piece parts for these are crazy expensive.

I ended up with this one from a 9B-17.



Overall it is in very good shape and included the input gears and drive shaft. The drive shaft was a huge bonus.

The drive shaft is set up for a power apron. (Has the key slot down the length) I have a feeling that all QCGB drive shafts will have this. The Logan 400 of course does not. The seller had the power apron as well but i do not see the need for a power apron on a 9" lathe that is not used daily and did not want to spend another $150. (Might as well just find a whole 9B.)

The parts arrived in good shape and my initial inspection showed that all was good. No broken gears, everything turned and could be adjusted. Great. The only down side is that the ID plate is in poor shape. It is readable but is a bit beat up. Will repair that later too.

Next steps. Tear it apart, clean, paint and start to figure out why it will not fit on the 400 as well as what i need to change or adapt to make it fit.

Matthew

 

[AR1911]

The casting number on the 9B box is on the inside, opposite the feed/speeds data plate. It's in big number, you can almost read it by feel. It's visible in one of Matt's photos above. I don't recall the number LA1201? but it was the same on the 9B and on the 11" Powermatic. That casting number should be an easy way to verify fitment.

I would reconsider that power apron. Power longitudinal feeds are much smoother and leave a uniform finish. Without the power apron you have to use the halfnuts. You will do better to preserve that precision for threading.
Also, parting off goes much better with power crossfeed. You have to prove it to yourself just like I did.
I would not have a lathe without power apron feeds.

 

[stevecmo]

+1 What Rex said. ^^^

 

[mjhenks]

Thank you for the guidance. I guess when using lathes at work (mind you i am not a machinist but an Engineer) i have never really used the power cross feed.

Three people have told me to re-consider.... I guess i will have to play with the power cross feed and see.

Can you explain what you meant by "Without the power apron you have to use the halfnuts."? Why would you use the halfnut more if you do not have power cross feed? I am sure if i had taken one apart i might understand.

 

[AR1911]

Can you explain what you meant by "Without the power apron you have to use the halfnuts."? Why would you use the halfnut more if you do not have power cross feed? I am sure if i had taken one apart i might understand.

Without power apron, you have two ways to move the cutter down the bed as it moves the cutter along the workpiece:

1 - crank it by hand, which leaves a non-uniform surface on all but the very shortest work
2 - Engage the halfnuts, which wears the leadscrew over time. It is also generally faster than an apron power feed.

If you have a power apron, that slot in the leadscrew drives a worm gear, which in turn drives the carriage longitudinally (or the cross-slide at 90 degrees) through the handwheel shaft and then to the rack. This is the 3rd option, which gives slower, uniform movement and does not use the threads of the lead screw.