Re: [CAD_CAM_EDM_DRO] motor speed/gear ratio

Brad,

You have a few options. The ones we spoke of already and another that I just thought of. If I were building a CNC rifling machine here is how I would go about it. I would use a long bed/table. I would mount a servo horizontally on one end with a chucking device to hold the barrel and then a steady rest on down the bed about 20". On the other end of the bed I would lay 1 or 2 THK rail(s) perfectly in line with the bore of the barrel (make it adjustable laterally) the length of the barrel plus the carriage. On the THK cars/slides machine an aluminum (a few pounds) block carriage to hold your rifling bar and mount to the THK slides. Determine the travel limits of the carriage and on each end of this mount an axle in pillow blocks. On each end of the axles mount a 3" no 35 pitch sprocket. Then loop a 35 chain around the sprockets and have one axle adjustable to tighten the chain. Now with a bracket off of each side of the carriage attach it to both chains ridgidly. on the far end of
the bed tooth belt a servo to that axle.

That would be a very light carriage and easy to attain the rapids you are designing for. I wouldn't suggest using a CNC rotary table for rotating the barrel as they are generally plagued with backlash issues. If the chain does not sound appealing then use long toothed belts instead. Frankly, I think the chain would suffice. The linear travel would not be as critical as the rotation due to the different angles i.e. helical pitch of the rifling.

Another option would be: Have some helical cams machined for different twists. Kick the carriage back and forth with air and hold the barrel fixed. But, I'm getting off topic.

Ron


nielsenbe@... wrote:
Thanks Ron,

What would you choose as a means to drive something 250 IPM? I guess that is
smoking a ball screw right along. I am not building a router, I am building a
rifling machine. I will have a rotary slaved off the the linear. That is why
the load will be around 50lbs, I need a stable platform with a rotary axis
mounted on it. That is also why I need as close to zero backlash as possible. I
will be running the cutter backwards down the same groove I just cut. I am open
to any suggestions since I am just starting to buy the components.

Thanks, Brad


[Non-text portions of this message have been removed]



Addresses:
FAQ: http://www.ktmarketing.com/faq.html
FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com

Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@..., timg@...
Moderator: pentam@... indigo_red@... davemucha@... [Moderators]
URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO

OFF Topic POSTS: General Machining
If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
http://www.metalworking.com/news_servers.html

http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.

NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
bill
List Mom
List Owner


Yahoo! Groups Links







---------------------------------
Do you Yahoo!?
Express yourself with Y! Messenger! Free. Download now.

[Non-text portions of this message have been removed]