[4]

Delta Rockwell 11" change gears

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

chucksue

Swarf
Registered
Joined
Mar 17, 2017
Messages
9
Likes
0
#1
I bought this lathe about 30 years ago. I have made lots of parts on this lathe. The problem is I can't cut threads on it. The gear arrangement is the same as in the photo posted by Thenrie. There is no number on the lathe. Where the two gears off the quick change for the feed rate of the tool is with two 48 teeth mine has one 40 tooth gear. I set up a dial indicator on the carriage and set the lathe for a 13 threads per inch cut.
I engaged the threading lever (with the motor not running) and turned the head one revolution by hand. My travel was .050 and it should be .07692.
The 24 tooth gear is on the shaft. I have the manual that came with the lathe. Am I right in assuming the 40 tooth gear is wrong and I need two 48 tooth gears to make it travel at the right rate to thread?
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,381
Likes
5,713
#2
Measuring the advance of the carriage for one revolution with a dial indicator can be difficult, but if you divide 1 by .050 you get 20... , so perhaps you are currently set for 20 TPI. It will be more accurate to measure, say, 10 revolutions and divide by 10.
 

chucksue

Swarf
Registered
Joined
Mar 17, 2017
Messages
9
Likes
0
#3
Yes by using ten it cuts down the error. I have put a 1/2 rod with 13 threads and watched the cutter track the thread . That is how I found out the feed was wrong. I know the selectors for 13 threads are set right. Thank you for your reply.
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,381
Likes
5,713
#4
Does the gear train start at the spindle, with all gearing visible to the QC box? Does it have a QC box?
 

chucksue

Swarf
Registered
Joined
Mar 17, 2017
Messages
9
Likes
0
#5
It has a quick change box. On Ebay there is a lathe posted like mine. www//ebay152118758114 . Gear train starts at the spindle. Has the reversing two gears to change the travel from left to right and right to left. They go thru a 60 tooth to a 24 tooth and then down to the QC which should have a 48 tooth gear. here is where mine has a 40 tooth gear. If you type in delta rockwell gear train and look at the images the gear train is shown. I don't know how to post the address.
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,381
Likes
5,713
#6
The reason I asked about the gear train is that it is all basic math. You have a lead screw with a certain pitch. Let's say it is 8 tpi, threads per inch. If you had gearing that overall made the ratio of spindle to lead screw one to one, then you would be making an 8 tpi thread. If you changed the gear on the shaft that drives the QCGB to one with twice as many teeth, then you would be cutting 16 tpi. The gears in the QCGB further change the gearing. Interestingly, the gears between the spindle and the QCGB shaft, excluding the spindle and QCGB shaft gears, all add up to zero unless there is a gear offset in the train where two gears are connected back to back and you are using one gear as the driving gear and another for the driven gear, then they count in the train. Otherwise, it does not matter if you have 12 or 100 teeth on a gear between the spindle gear and the QCGB shaft gear, the ratio will not change there. Is the QCGB missing the threading chart? If it is there, how about posting a picture of it? If not, we will need to know the model of the lathe to possibly be able to help you.
 

chucksue

Swarf
Registered
Joined
Mar 17, 2017
Messages
9
Likes
0
#7
The QC chart is there.It is in great shape. The tag for the model is gone. I think it is a 25-100. I found that by just searching the net. I used the formula ( gear # teeth plus two divided by the diameter of the gear ) and found that all the gears have a DP of 16.
I will try to take some pictures and post them.
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,381
Likes
5,713
#8
If the QC chart is there, just do as it says...
 

chucksue

Swarf
Registered
Joined
Mar 17, 2017
Messages
9
Likes
0
#9
That is where I found out the feed rate was not 13 threads per inch. I think that is where the 40 tooth gear on the QC shaft is messing me up.
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,381
Likes
5,713
#10
The chart should show the gears required and the tumbler positions for the various threads. As Captain Piccard would say, "Make it so."
 

chucksue

Swarf
Registered
Joined
Mar 17, 2017
Messages
9
Likes
0
#11
Samsung 1 745.jpg Samsung 1 746.jpg
Here are some pictures. Boston Gear will not sell to an individule.
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,381
Likes
5,713
#12
The gearing is compound. You will need the manual for the lathe to see the exact change gear setup needed. The data plate for the QC gearbox says that the "stud gear" needs to be 24 teeth. You have the quick change handles in the correct position. Get the change gear train correct and it should give you 13 TPI. Any bearing shop can purchase from Boston Gear. Lots of other businesses, too. You can call Boston Gear at 800-825-6544 and ask for the dealers in your area. There is also a dealer locator on their web site:
http://www.bostongear.com/distributor-locator
 

chucksue

Swarf
Registered
Joined
Mar 17, 2017
Messages
9
Likes
0
#13
I have a set of 48 tooth gears coming. The manual shows the gear on the QC shaft should be 48.
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,381
Likes
5,713
#14
I have a set of 48 tooth gears coming. The manual shows the gear on the QC shaft should be 48.
Cool! Tell us when you have success on your 13 tpi thread.
 

chucksue

Swarf
Registered
Joined
Mar 17, 2017
Messages
9
Likes
0
#15
Installed the gears from a man in Michigan. We can now cut threads. The gears were nice and not expensive.
 

Kroll

Active User
H-M Supporter - Gold Member ($25)
Joined
Dec 23, 2012
Messages
982
Likes
230
#16
Guys I know this is an old thread but I was told that the DP for the QCGB is 20 and all the other gears on the lathe is 14.5 Myself I don't know one way or the other.
 
D

Deleted member 473

Guest - Please Register!
Guest - Please Register!
#17
Get with our member 100LL. I believe he has a 11" Rockwell Lathe. He might be able to help you on the DP used on your lathe. He's located on the west side of Houston, too. Ken
 

100LL

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Aug 20, 2015
Messages
110
Likes
44
#18
Pretty sure the outboard gears are DP 16. Not sure on the QCGB. Hadn’t thought of that. Going to difficult to measure as well. I’ll look in the parts breakdown.
 

rodm717

Swarf
Registered
Joined
Sep 1, 2017
Messages
20
Likes
10
#19
Guys I know this is an old thread but I was told that the DP for the QCGB is 20 and all the other gears on the lathe is 14.5 Myself I don't know one way or the other.
There are manuals on Yahoo Delta/Rockwell group. Both 24 and 48 are standard stud gears and both are needed for full threading range, if you look at chart on gear box. 48 is needed for 4- 7 tpi and 48 for the rest.
 
[6]
[5] [7]
Top