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Author Topic: Joining_linear-rails?  (Read 4221 times)

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Offline Garyv

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Joining_linear-rails?
« on: April 29, 2008, 03:08:46 PM »
Can_linear-rails_be_connected_end_to_end_without_loss_in_accuracy_or_will_they_bounce_when_
going_over_the_joint?
I_am_going_to_re-build_my_wood_router_and_use_a_steel_tubing_frame_like_a_shop-bot_after_building_
one_with_an_MDF_frame_I_just_dont_get_the_quality_of_cuts_with_it_in_MDF_like_I_wanted_and_pretty_much_new_
that_this_was_a_prototype_anyway_but_I_want_to_go_with_linear_beaarings_this_time_and_have_seen_a_lot_
of_smaller_pairs_of_linear_bearings_that_If_they_will_work_if_I_connect_end_to_end_will_save_me_some_money_on_bearings..
Thanks
Gary
Re: Joining_linear-rails?
« Reply #1 on: April 29, 2008, 06:37:45 PM »
Hi Gary,
Anything is possible. the trick might be to make sure you have identical linear rails (!) and accurately machine a surface to mount them on. The best method is to have the rail mounts machined in position on the machine bed.  This can be easily done be an engineering company with a large mill.  Can be expensive but it is worth it.  Because the mounting rails will then be accurate and true, anything you mount on the rails should also be spot on. ( or as near as you can hope for. ) The key to accuracy is rigidity - make the frame solid and everything else follows. Having an accurate face and edge for the rail to mount against should enable you to add rails end to end.

Bruce

Offline zarzul

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Re: Joining_linear-rails?
« Reply #2 on: April 30, 2008, 11:51:07 AM »
Like Bruce said it can be done.  Since each truck has a dozen+ balls in contact with the race at once, only one ball will feel the joint at a time.    I joined several in my router table build and it is pretty much bumpless,  I can hear a tic as I push it over the joint but I can't feel it.  At first I carefully milled the end of the first two that I joined and then bolted them down butted together but then the next two I just joined them without milling, I can't tell any difference since only one ball is at the joint at a time anyway.

I am still building and have not tested it on material yet,  just running the steppers back and forth, still working on electronics & wiring.

Arnie

Offline Garyv

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Re: Joining_linear-rails?
« Reply #3 on: May 01, 2008, 08:28:53 AM »
Thanks_for_the_replies_guys..
I_find_sets_on_ebay_cheaper_in_sets_of_4_of_the_same_then_I_do_with_just_2_long_ones..
Thanks
Re: Joining_linear-rails?
« Reply #4 on: October 07, 2008, 04:53:07 AM »
I have extended rails in the past with no effect on accuracy. But just as mentioned the alignment is the key. mill or grind the ends to match as close as possible.