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4

Cx701 Change Gears - Oem Gear List And Additional Threading Options

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jimbojones132

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#1
Having owned a used CX701 for a little, wasn't sure if I had the complete set of gears that was supposed to have come with the lathe. Also, was very disappointed to see that if you have the 8tpi leadscrew machine, you only get 13 change gears (vs 14 change gears sold with competitors 11x27 lathe), no change gear setup for 13tpi threading and the metric threading chart only shows 8 possible mm threads..

Well, here's a few discoveries that I made that I wanted to share:
1) CX701 comes with 13 gears (5 installed/8 spares); Here's what the list of change gears you're supposed to get with the CX701 (in teeth): 20, 25, 30, 40, 45, 50, 55, 60, 63, 70, 75, 80, 80

2) there is an OPTIONAL 65-tooth gear that you can order from Busy Bee ($30 - part # PCX70165T) that will allow you to cut true 13tpi threads. You CAN cut a 12.99TPI thread with the OEM change gears but Busy Bee doesn't publish what that gearing combination is and would rather sell you an extra gear. Consider that some of their other threading options aren't 100% accurate also, some people may feel its not worth buying the extra gear. One thing I will say is that the 65T gear does increase accuracy on some other gearing changes so if you're wanting to increase precision/have a few more threading options, it's something that is available.

3) this lathe apparently is manufactured in 2 configurations: SAE model with 8tpi leadscrew w/13 OR 14 change gears and a metric leadscrew version (unsure of the rod pitch) w/14 change gears. Have only seen the BusyBee-branded lathe in the SAE version/13 gear and the change gear plate on the machine refers solely to that. However, in the manual, it shows BOTH Metric and SAE leadscrew model charts. One thing that becomes quickly apparent is that, if you bought the SAE/CX machine, it shows only half of the metric threading combinations vs Metric leadscrew model and you say to yourself 'geez...wished they would have provided the metric leadscrew model instead'. Fear not...the SAE model chart is simply missing what the gearing combinations are...you CAN make most of the Metric thread pitches you see on the metric-rodded machine (except the ones that require the 65T gear). I assembled some change gear programming software and configured it to suit the CX701 and it claims I can make 16 of the most-common metric threads with OEM/13 gears and up to 24 metric threads (some also using the 65T) with <1% error. Unsure why Busy Bee or their supplier makes the SAE model look so limited on the metric threading side...will have to manually fit some of these gearing combinations to double-check but the math says its possible to make many more Metric threads than what the chart shows.

Speaking of the change gear software, it is adjustable e.g. can be used for other lathes with different number of change gears, different pitched threaded rod, etc and works better than any of the software/change gear web pages I could currently find on the Internet. Most change gear web pages only work for smaller lathes and dont have the same gear layout possibilities as the CX701/PM1127 . I'm willing to help people figure out gearing combinations but am not ready to share the program at this time (spending my time unemployed, handing out software, isn't something I can live on).

If anyone is curious if there is a change gear combo for an unlisted pitch on their machine (TPI or mm), shoot me a message with: 1) list of change gears you have 2) number of gear teeth on the spindle (e.g. CX701 has 40) 3) the pitch of the leadscrew on their machine and I'll see if I can calculate a useful change gear combo; note: the combination may not produce 100% accurate thread but I'll tell you what the actual calculated thread is and you can decide for yourself if it's accurate enough....most of them I can get down to the sub-1% error range as long as you have a complete set of gears.
 
Last edited:

3dshooter80

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#2
I own a pm1127vflb aND I am very interested in the additional metric capabilities. Do you have a chart by chance? I realize you don't eant to give out the software, and I am not interested in the software. I am interested in .7 mm for example.
 

bmw rider

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#4
My list of gears is a little different than yours: 25, 30(x2), 40, 45, 50, 55, 60, 63, 70, 75, 80(x2). I have the imperial 8tpi lead screw. I may look into the extra 65t gear.
 

jimbojones132

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#5
re: duplicate 30T and missing 20T change gear: if you check your facing chart (2nd config), it shows a gear setup using the 20T gear so fairly certain they messed up in providing the correct gears in your set.

Missing the 20T impacts the ability to change-up for smaller metric thread pitches (which are not shown on the chart). Check with BB as they do carry some of the gears besides the 65T but I would be surprised if they will provide it for free.
 

bmw rider

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#6
I'll have a look at the charts, but it's not really a big issue presently as I don't do much (any) thread cutting. Most of what I do I can work with taps and dies easier. Ideally if I were going to be doing any amount of thread cutting, a quick change gearbox lathe would be the preference. If anything, the ability to cut 13tpi would be something I might use.
 

jimbojones132

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#7
Even though I use tap/die for re-threading, I've always found it hard to use a die to get a thread squarely started on a un-threaded rod. Not a big issue if you're simply spinning a nut on it later but I was attempting to make a center post for the QCTP on my lathe and indeed, the threads I made by using a die were off-square and caused the QCTP holder itself to be off-square. Also, I needed to cut a 1.75mm thread for another application (which isn't on the OEM threading chart) so I figured I'd resolve all of the issues by using the lathe to at least make a starter thread for the die...and thus had to make the program to calculate the change gear config since so few metric threads are listed on the machine.
 

bmw rider

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#8
I just discovered another missing gear that needs to be in the list. There should be two of the 60T gears. I was setting up to do a M22 1.5 thread and the chart shows it needing two 60t gears to get that pitch. Off to Busy Bee today to see if they have or can get it for me. May as well get the other gears to complete the set while I'm at it. It's a nuisance to have to put a project on hold due to incomplete tooling. And of course the piece I'm making is a tool to facilitate a repair on my motorcycle, so that job is also on hold.
 

bmw rider

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#10
Once I rechecked the chart I realized that what I was mistakenly reading was the "metric" chart which is actually for the metric lead screw equipped lathes. I found the correct gear set up on the inch chart and successfully cut the threads I needed. The job is done and my bike is back in service.

2016-08-29%2015.17.09.jpg
 
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