CAD CAM EDM DRO - Yahoo Group Archive

Re: Guides

Posted by Ross
on 2003-05-14 10:02:22 UTC
Alex...

Like I said earlier, I'm having good luck with chain driven leadscrews. The reason I went with leadscrews over a chain loop drive was for machine resolution. I forget the exact numberes, but a roughly 1" pitch diameter sprocket driving the gantry directly in a loop would have only delivered .002 or so per step. I wanted more than that, which meant some sort of reduction drive...and lead screws were the simplest way.

Someone mentioned chain stretch. The chains will stretch, but only to a certain point. It's like a motorcycle chain. You constantly adjust the cahin in the first 1000 miles. After that, you might adjust once a year.

I adjusted the chains on my machine 3 times in the first week of steady operation. In the past 3 weeks, I have not noticed any excessive play in the chains. The thing I noticed about roller chain is that they do not have to be guitar string tight. I found that the machine runs better with a little play in the chains and when measured with a dial indicator, has no more backlash than with a tight chain.

All that said....If I had been able to find timing belts in the right lengths, I would have gone that way instead.

I would stay away from HD casters for rollers unless you're building a plasma or flame cutting table where accuracy is just not important. The problem with those casters is that the wheel can be quite a bit out of round. In some cases so far out that you can see it by eye. That will cause your Z height to vary all over the place as the gantry moves.

You can buy sealed roller bearings from MSC Industrial for $2 or so each. They make great roller guides. MSC also sells cold rolled flat stock which would work great for the rails.

Ross

Discussion Thread

alex 2003-05-12 17:00:54 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides indy123456 2003-05-12 20:08:28 UTC Re: Guides dcdziner 2003-05-12 20:30:11 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides John Craddock 2003-05-13 01:31:08 UTC RE: [CAD_CAM_EDM_DRO] Re: Guides alex 2003-05-13 07:41:18 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides Harvey White 2003-05-13 08:29:29 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides JanRwl@A... 2003-05-13 13:31:02 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides alex 2003-05-13 13:42:42 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides JanRwl@A... 2003-05-13 14:50:27 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides alex 2003-05-13 15:02:02 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides turbulatordude 2003-05-13 15:57:04 UTC Re: Guides alex 2003-05-13 16:04:04 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides Ross 2003-05-13 17:06:43 UTC Re: Guides turbulatordude 2003-05-13 17:11:56 UTC types of timing belts ( was Re: Guides alex 2003-05-13 19:19:11 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides JanRwl@A... 2003-05-13 20:40:20 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides alex 2003-05-14 06:50:16 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides David A. Frantz 2003-05-14 07:20:49 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides alex 2003-05-14 07:38:08 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides wayne_j_hill 2003-05-14 08:02:30 UTC types of timing belts ( was Re: Guides turbulatordude 2003-05-14 09:57:47 UTC Re: Guides turbulatordude 2003-05-14 09:58:23 UTC types of timing belts ( was Re: Guides Ross 2003-05-14 10:02:22 UTC Re: Guides alex 2003-05-14 10:31:34 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides Harvey White 2003-05-14 12:53:11 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides forumtvm 2003-05-14 16:58:29 UTC Re: Guides Harvey White 2003-05-14 19:39:56 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides Don Rogers 2003-05-14 19:43:01 UTC Re:Guides turbulatordude 2003-05-15 05:56:24 UTC Re:Guides Ross 2003-05-15 06:12:09 UTC Re:Guides alex 2003-05-15 14:40:42 UTC Re: [CAD_CAM_EDM_DRO] Re: Guides