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blakekoehn
Sun 24 January 2010, 15:38
Do you paint the rails and then mount the rack with the double sided tape or do you degrease the rails and mount the rack and then paint?

I know the tape will hold the rack because I work with that tape a lot in my sign business, but the tape is only as good as the paint underneath.

Does that paint wear out of the rack pretty quick or should I mask the rack if I paint after it is installed?

Thanks

lunaj76
Sun 24 January 2010, 17:11
Blake,

I masked the v on the rails and painted only the tops. Then mounted the rails to the table and gantry then mounted the unpainted racks to the rails. Do not paint the racks!.

KenC
Sun 24 January 2010, 20:16
Oh no... I'd painted the rail with Hammerite... now I have to strip the paint?

Gerald D
Sun 24 January 2010, 23:21
We used the tape onto paint, but we made sure the rails were properly painted.

Check a sample to see if it peels your paint. If paint peels, it is a bad paint job, period! :)

KenC
Mon 25 January 2010, 01:17
Thanks Gerald.

lunaj76
Mon 25 January 2010, 07:31
We purchased tape that was spected for metal to metal. That is why we didn't paint the underside of the rails.

timberlinemd
Sat 15 May 2010, 15:39
I'm having a little trouble getting a tap that has a flat. What is the down side if I just drill straight thru the rack and tap it with a thru tap?

timberlinemd
Sat 15 May 2010, 19:18
My solution was to take another tap the same size, cut it off, grind till flat!

Gerald D
Sat 15 May 2010, 22:31
Steve, you should be tapping the rail, not the rack.

timberlinemd
Sat 15 May 2010, 22:43
Gerald, for the X & Y you are correct. For the Z rack they are tapped. Must they be blind?

Gerald D
Sat 15 May 2010, 22:53
Oops, forgot the Z. :o

You can drill through and tap through, no problem.

A standard "bottom" tap, the third one in a set of three, is the normal tap for a blind hole and it cuts a full thread until about 5 thread pitches from the bottom.

timberlinemd
Sun 16 May 2010, 09:27
Thanks Gerald. Most of the tap sets sold around here only come with one tap. I'm sure that a true machinery supply would carry the full set. The taps that go straight thru are easy to fine even at home centers. My solution was to take another tap that was designed to be used as a straight thru tap, cut off the tip and grind it down until it had a flat bottom. It worked really well!

Gerald D
Sun 16 May 2010, 10:10
I must admit that the blind hole is not so friendly for the non-metric guys with 1/2" racks and 1/4" screws. (small rack, biggish screw). For us metric guys, it is a 15mm rack with a 6mm screw.....a bit easier.

I think I spoke too quickly when a said to drill right through. You will loose half of a tooth when you do this, and I don't think that is okay for a rack that is only 1/2" wide. In other words, you end up with a 1/4" wide tooth [6.35mm]. The metric guys, on drilling through, will still have 9mm tooth width.

chopper
Mon 17 May 2010, 16:57
why not just weld them on,
you will not need to worry if they will let go, this is what I did...
//chopper

Gerald D
Mon 17 May 2010, 20:24
We have replaced a worn out Z-rack already, because it does a lot of movement in a short distance. (Actually, we had already turned it end-for-end first). Don't like the idea of welding, or taping, it on. However, our pinion gears are hardened and this shortens the rack life.

bradm
Mon 17 May 2010, 21:37
Hmm. Does it matter how often the through drilled and tapped portion of the rack is actually used, and/or if it's ever used under cutting load as opposed to just for clearance during rapids?

Gerald D
Tue 18 May 2010, 00:26
Depending on a particular user's setup (router bracket, cutter length, table top thickness, etc), the rack is typically loaded in the vicinity of the upper screw. Not a good idea to have a weak tooth there.