-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
I Might Become a Machinist
- Thread starter ddickey
- Start date
- Joined
- Sep 29, 2014
- Messages
- 2,102
Good Luck
A BP Romi lathe I suspect, been running one for about 5 years or so, nice machines with a very simple to use conversational control. I found the users manual not very useful however.
If you have questions ask and I will tell you what I know.
Finished my part. It had four steps with reliefs after each step. 4.75" long with the largest step 1.4375". Center drilled both ends to .270".
I hit all the dimensions within spec. +-.002" was the tightest tolerance. It was .01" for the reliefs, .005 for the length of the steps. At the end the instructor sets it up between centers and check that TIR is no more than .002". I do not know the result of that but I had it dialed with the 4J.
The BP-Romi was a treat to run. Only thing I didn't like how close the carriage hand wheel was to the cross slide wheel. Love those wide lathes.
I hit all the dimensions within spec. +-.002" was the tightest tolerance. It was .01" for the reliefs, .005 for the length of the steps. At the end the instructor sets it up between centers and check that TIR is no more than .002". I do not know the result of that but I had it dialed with the 4J.
The BP-Romi was a treat to run. Only thing I didn't like how close the carriage hand wheel was to the cross slide wheel. Love those wide lathes.
- Joined
- Sep 29, 2014
- Messages
- 2,102
Good to hear it went well.
The BP-Romi lathes will begin to creep up on the diameter after 3-4 hours of constant running but usually less then .002-003" during an 8 hour day.
Beware that when turned off at night they may lose position when restarted the next morning, this can be unpleasant at best.
The BP-Romi lathes will begin to creep up on the diameter after 3-4 hours of constant running but usually less then .002-003" during an 8 hour day.
Beware that when turned off at night they may lose position when restarted the next morning, this can be unpleasant at best.
Wreck wreck,
I did have to make some adjustments as it did seem creep up. Makes sense now, thanks.
Mikey I'm pretty confident I passed the project today and the oral evaluation yesterday.
However I'd be surprised if I passed the written exam. 109 questions in three hours.
It was mostly repairman questions, maybe 15% machining questions.
I don't think the written exam will exclude you from the application process though.
I did have to make some adjustments as it did seem creep up. Makes sense now, thanks.
Mikey I'm pretty confident I passed the project today and the oral evaluation yesterday.
However I'd be surprised if I passed the written exam. 109 questions in three hours.
It was mostly repairman questions, maybe 15% machining questions.
I don't think the written exam will exclude you from the application process though.
- Joined
- May 4, 2015
- Messages
- 3,583
Good luck , before being able to go to vocational school , we had the tests apt, math, verbil and more . On the mechanical aptitude part ,, not bragging,,, but the said I tested in the genius range. YUPP no problem getting in vokie, I hated school and was good with tools. Freshmen year you had six programs three you picked three they picked from your testing. I was asked to come back to four of the different types of work. Stationary engineering I aced he wanted me to take the four year course, plumbing another , machine tool and die was my choice , which for me ment two years in the tool and die , and one year in the machine shop. Then two years more for apprenticeship and more to become a tool and die machinist. It's a great job for anyone , I enjoyed my work in the different shops. Stick with the tuff ones you'll learn the most there. Work hard study your weak areas and keep learning.
- Joined
- Sep 29, 2014
- Messages
- 2,102
Began an internal threading job on one of these lathes before I left today, 1 1/2-12 X 2 1/2" deep in the end of a rectangular steel part 3" X 3 7/8" X 8 1/2" long held in a 4 Jaw.
Don't ask why this is being done in a lathe rather then being drilled and tapped, they gave me a brand new GO-NO GO plug gauge for 4 parts. The gauge cost far more then a tap.
The canned thread program looks like this, all values may be changed.
ID = 2 (as a side note, in the tool library all tools are defined as OD Rough, ID Rough, OD groove, ID groove, Internal Thread and External Thread, if you choose a tool stored as External Thread for an ID threading job it will crash in spectacular fashion) keep this in mind. Also when programming a facing operation the roughing screen will give you 3 options,1 = OD, 2= ID and 3= Face, the Finish/Profile screen gives 2 options, 1 = tool on the left and 2 = tool on the right, if either choices are wrong it will often crash hard.
Lead = 12 TPI or .0833333, one may toggle between TPI and Lead, I always use lead, (this allows you to make a 3/8-16 1/4 thread so as to confuse someone in the future)
Thread Height is calculated by the control, I don't trust it so change it to a slightly smaller value like .o42"
Step= First pass DOC
Step 2 = All subsequent passes
Minimun Step = The last pass DOC
Spring Passes need no explanation
Withdrawal Clearance = The distance the tool moves away after each pass, this helps with chip clearance, keep in mind that when boring with a tool that fits closely in the hole to much clearance will cause the back of the tool to crash into the back side of the bore, this value is distance from the surface so .100" clearance is .200" on the diameter.
Engage Angle = The angle at which the tool advances much like manual threading from the compound
Start Z = Where the tool rapids to before threading begins, in this case .200" + .100" clearance or .300" from Z 0.000", (all moves toward the spindle from Z 0.000 are negative) a spindle encoder tells the Z servo when to start moving in relation to the spindle position, there is no gear train between the spindle and lead screw, you may put it out of gear between passes and it will not effect the position so long as you do not turn the power off or load another program, a blackout will screw you however, pun intended.
End Z = Where the thread ends, make this less then the blind bore, crashing a threading tool into a shoulder or the bottom of a bore is unproductive. Use an undercut at the end of the thread when possible.
Start Diameter = What it says, Minor Diameter of an internal thread or Major Diameter of an external thread.
End Diameter = The ability to make a tapered thread such as NPT, you are on your own when calculating these values. I have my methods of doing so.
In as much as the machine will do most of the work one must still set up the work set the tool, input the parameters and measure the thread just like doing it manually yet without all of the pesky 1/2 nut work, it is a thing of beauty.
Don't ask why this is being done in a lathe rather then being drilled and tapped, they gave me a brand new GO-NO GO plug gauge for 4 parts. The gauge cost far more then a tap.
The canned thread program looks like this, all values may be changed.
ID = 2 (as a side note, in the tool library all tools are defined as OD Rough, ID Rough, OD groove, ID groove, Internal Thread and External Thread, if you choose a tool stored as External Thread for an ID threading job it will crash in spectacular fashion) keep this in mind. Also when programming a facing operation the roughing screen will give you 3 options,1 = OD, 2= ID and 3= Face, the Finish/Profile screen gives 2 options, 1 = tool on the left and 2 = tool on the right, if either choices are wrong it will often crash hard.
Lead = 12 TPI or .0833333, one may toggle between TPI and Lead, I always use lead, (this allows you to make a 3/8-16 1/4 thread so as to confuse someone in the future)
Thread Height is calculated by the control, I don't trust it so change it to a slightly smaller value like .o42"
Step= First pass DOC
Step 2 = All subsequent passes
Minimun Step = The last pass DOC
Spring Passes need no explanation
Withdrawal Clearance = The distance the tool moves away after each pass, this helps with chip clearance, keep in mind that when boring with a tool that fits closely in the hole to much clearance will cause the back of the tool to crash into the back side of the bore, this value is distance from the surface so .100" clearance is .200" on the diameter.
Engage Angle = The angle at which the tool advances much like manual threading from the compound
Start Z = Where the tool rapids to before threading begins, in this case .200" + .100" clearance or .300" from Z 0.000", (all moves toward the spindle from Z 0.000 are negative) a spindle encoder tells the Z servo when to start moving in relation to the spindle position, there is no gear train between the spindle and lead screw, you may put it out of gear between passes and it will not effect the position so long as you do not turn the power off or load another program, a blackout will screw you however, pun intended.
End Z = Where the thread ends, make this less then the blind bore, crashing a threading tool into a shoulder or the bottom of a bore is unproductive. Use an undercut at the end of the thread when possible.
Start Diameter = What it says, Minor Diameter of an internal thread or Major Diameter of an external thread.
End Diameter = The ability to make a tapered thread such as NPT, you are on your own when calculating these values. I have my methods of doing so.
In as much as the machine will do most of the work one must still set up the work set the tool, input the parameters and measure the thread just like doing it manually yet without all of the pesky 1/2 nut work, it is a thing of beauty.
Last edited: