Miguels244
Diamond
- Joined
- Mar 27, 2011
- Location
- Denver, CO USA
The following discusses the change gears on the Sag14.
Specifically my sag14...see thread here.
(Insert link)
Mine is a Hercules clone.
Use this information at your own risk, this only applies to my clone.
The Hercules has only two ranges in the QC box...later Graz seem to have 4 and may need other gear sets.
In order to switch from metric to inch follow the directions on the plaque. In addition to setting the correct control positions the change gears need to be changed to match the plaque as well. Find the manual on line somewhere.
(Insert images here)
The problem arises when, like me, you don’t have the original change gear set.
A perennial problem with buying a lathe.
Mine came with the metric set.
Since the Graziano is European its native is metric.
So, the metric is simple.
20T on the spindle -> a 40T idler -> 80T drive into the QC box.
As shown on the QC plaque, although it omits the idler.
(Insert picture)
To drive the QC at inch rates a different gear train is needed.
The plaque shows...
31T spindle ->
58 driven/ 47 driver ->
64T QC box drive.
(Insert picture)
These gears measure as mod 1.0,you are on your own for pressure angle.
My recollection is that metric is almost always 20*.
Now.
The ratio of the inch change gears is...
(31/58)*(47/64)=0.39251
As any nerd can tell you that’s not quite right.
That gives us a ratio of 2.548 not the defined 2.54.
Not to worry though that gives us an error of 0.3% or 3parts per thousand.
Over an inch that becomes 0.003 error...so don’t use the screw cutting for depth measurement, and it may throw off your clocking if you are doing something weird and long. Cutting a 10” lead screw would throw you off by 0.030.
I’m assuming there isn’t a 3:1000 gearset in the QC box some where to correct for the error.
When I buy/build or steal a gear set I’ll mearure it and update this post.
On topic questions and comments only please.
Give it a few days for pictures.
Specifically my sag14...see thread here.
(Insert link)
Mine is a Hercules clone.
Use this information at your own risk, this only applies to my clone.
The Hercules has only two ranges in the QC box...later Graz seem to have 4 and may need other gear sets.
In order to switch from metric to inch follow the directions on the plaque. In addition to setting the correct control positions the change gears need to be changed to match the plaque as well. Find the manual on line somewhere.
(Insert images here)
The problem arises when, like me, you don’t have the original change gear set.
A perennial problem with buying a lathe.
Mine came with the metric set.
Since the Graziano is European its native is metric.
So, the metric is simple.
20T on the spindle -> a 40T idler -> 80T drive into the QC box.
As shown on the QC plaque, although it omits the idler.
(Insert picture)
To drive the QC at inch rates a different gear train is needed.
The plaque shows...
31T spindle ->
58 driven/ 47 driver ->
64T QC box drive.
(Insert picture)
These gears measure as mod 1.0,you are on your own for pressure angle.
My recollection is that metric is almost always 20*.
Now.
The ratio of the inch change gears is...
(31/58)*(47/64)=0.39251
As any nerd can tell you that’s not quite right.
That gives us a ratio of 2.548 not the defined 2.54.
Not to worry though that gives us an error of 0.3% or 3parts per thousand.
Over an inch that becomes 0.003 error...so don’t use the screw cutting for depth measurement, and it may throw off your clocking if you are doing something weird and long. Cutting a 10” lead screw would throw you off by 0.030.
I’m assuming there isn’t a 3:1000 gearset in the QC box some where to correct for the error.
When I buy/build or steal a gear set I’ll mearure it and update this post.
On topic questions and comments only please.
Give it a few days for pictures.