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Forum Driving Mechanisms: Rack/pinion, gears, screws & chains Rack & Pinion U.S.A manufacturer/supplier

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Thread Last Poster Posts Pages Last Post Archive through November 18, 2006 DocTanner 25  1  11-18-06  12:00 am   Closed: New threads not accepted on this page

Author Message   Gerald_D Registered Username: Gerald_d Post Number: 478 Registered: 11-2005 Posted on Saturday, November 18, 2006 - 07:08 am:        Seeing that stdsteel doesn't sell gear wheels to run on their racks, they should be able to give great advice on where to get economical pinions.   Herb Lichtenberg Registered Username: Hflwaterski Post Number: 1 Registered: 11-2006 Posted on Thursday, November 30, 2006 - 05:56 pm:        What does the length of the rack need to be on the main table x-rail? Most suppliers only have racks 60-72" long. I'm beginning a build and putting together a list of supplies that I need to order. I'm completely new to all of this so I apologize if this is a dumb question. After looking at your site for months, I've been inspired to build your machine. Not to mention I have good relations with friends in the CNC laser and milling machine areas. That helps!   Gerald_D Registered Username: Gerald_d Post Number: 557 Registered: 11-2005 Posted on Thursday, November 30, 2006 - 06:12 pm:        Hi Herb, drawing M2 10 110 W tells you how to join racks, and also tells you that the X-rack must be the length of your table top (X) plus 200mm [7.9"]. The 60-72" racks are pretty standard, but they can easily be joined. You use a 3rd piece of rack as a jig, or template....... Having friends as suppliers is always useful!   vadeem Registered Username: Vid1900 Post Number: 24 Registered: 10-2006 Posted on Tuesday, December 05, 2006 - 10:03 am:        [quote]I have gone through the Boston gear catalouge. As per your specs mentioned in anothe thread I assume I have found the correct pinoin and rack. For the Pinion the Catalogue page no is 30 and the item code is 46133. For the Rack the Cat page number is 35 and the item code is 12760 (6 foot lenth).[/quote] Someone asked me why the page #s were wrong. The pages fabrica quotes are the printed page #s at the bottom of the catalog, not the PDF page numbers in the Adobe box. Just to make it easy on everybody...   Greg Holt Registered Username: Greolt Post Number: 11 Registered: 08-2006 Posted on Friday, December 08, 2006 - 02:56 am:        What have you found to be the best way to attach the rack to the angle iron? Looked at the PDF and it appears as one bolt either end (I think) Thanks.   Gerald_D Registered Username: Gerald_d Post Number: 609 Registered: 11-2005 Posted on Friday, December 08, 2006 - 07:14 am:        Drawings 1010200A and 1020200A refer. Good double-sided tape along the whole length - the bolts are only for belts & braces. 3M is the only brand name that I know making quality tapes. Use 2mm thick tape. Make sure that the metal surfaces are properly degreased before applying adhesives or paints.   joe Registered Username: Joecnc2006 Post Number: 2 Registered: 05-2006 Posted on Sunday, February 18, 2007 - 09:13 am:        What is the resolution of the Mechmate using the 20 pitch, direct drive 20 tooth pinion? I take it that is 20 teeth per inch?   Gerald_D Registered Username: Gerald_d Post Number: 927 Registered: 11-2005 Posted on Sunday, February 18, 2007 - 02:00 pm:        Not 20 tpi....see this thread: http://www.mechmate.com/Forum/messages/12/3255.html   Brian_B Registered Username: Allegheny Post Number: 33 Registered: 07-2006 Posted on Sunday, February 18, 2007 - 06:29 pm:        Hi Gerald, Has anyone given any thought to using helical rack and pinions? Supposedly less likely to skip a tooth and with better/more efficient power transmission. According to this company: http://www.atlantadrives.com/racks.htm they are no more expensive than normal straight racks (though I don't know, yet, what their "normal" pricing is!). The main disadvantage is that they can be tricky to align and set up. Brian   Gerald_D Registered Username: Gerald_d Post Number: 932 Registered: 11-2005 Posted on Monday, February 19, 2007 - 07:29 am:        Brian, we are not in the habit of skipping teeth with the straight rack, so we don't need improvements in that area. The springloaded pinion will have a smoother ride on a helical rack compared to a straight one. But a helical rack introduces side forces, or an axial force on the pinion shaft. Most stepper motors have a lot of axial freeplay (temperature dependent) which will translate to backlash with a helical gear train. The oriental motor gearboxes also don't want axial forces on their shafts.   Hugo Carradini Registered Username: Hugotel Post Number: 41 Registered: 11-2006 Posted on Thursday, February 22, 2007 - 11:04 pm:        Gerald, sorry to bother but I am having problems with the pinion. I am buying Boston Gear (Rack L2020 6´) but I am confused with the pinion I was thinking in Boston Gear (pinion YA20) but I am not sure because it seems don't have screws to tigt up. ¿Can you please help me with the right pinion I should get from Boston Gear. I appreciate your effort and and I am pleased to tell that I am buying all my stuff I am importing next monday.   reza forushani Registered Username: Reza Post Number: 52 Registered: 01-2007 Posted on Thursday, February 22, 2007 - 11:24 pm:        Hugo I ordered pinions twice by mistake. If you need it, I can send it to you. They don't the screw but you can ad that.   Hugo Carradini Registered Username: Hugotel Post Number: 42 Registered: 11-2006 Posted on Friday, February 23, 2007 - 12:41 am:        Thanks reza. The only problem is that i have to send things to Miami and then from there I have a courier and they send it to me. Little complicate but things get lost when I have them send strait to me . ¿You buy the YA20 and fitted OK? I guess I can make the treads to fit. Thanks   reza forushani Registered Username: Reza Post Number: 53 Registered: 01-2007 Posted on Friday, February 23, 2007 - 01:06 am:        Yes they fit perfect. I bought from Mcmaster but its is a Boston Gear, I will look up the model# and post it for you.   Gerald_D Registered Username: Gerald_d Post Number: 978 Registered: 11-2005 Posted on Friday, February 23, 2007 - 06:59 am:        Making the threads in the gear is easy. Finding good "grubscrews" in your country is maybe not so easy. Most grubscrews everywhere are normally okay, but some rare times we find soft grubscrews which are real junk. Make sure you can get good hard ones.   eloid Registered Username: Eloid Post Number: 3 Registered: 02-2007 Posted on Friday, March 02, 2007 - 05:57 am:        14 1/2° and 20° pressure angle spur gears and racks which is better and why?   Gerald_D Registered Username: Gerald_d Post Number: 1078 Registered: 11-2005 Posted on Friday, March 02, 2007 - 07:04 am:        14.5 has less chance of jumping out, but more chance of breaking off. For a spring-loaded ride, the 20 runs smoother.   Bill McGuire Registered Username: Johnnydoughey Post Number: 12 Registered: 12-2006 Posted on Friday, March 16, 2007 - 12:56 am:        Gerald... According to the drawings and posts, the racks are attached to the rails with the two end screws and double sided tape. Is there a reason one should not attach the racks (on the X axis) to the channel iron, rather than the rails? Thanks...   Gerald_D Registered Username: Gerald_d Post Number: 1153 Registered: 11-2005 Posted on Friday, March 16, 2007 - 05:58 am:        Hi Bill I sense some nervousness about the double-sided tape..... The channels are not an accurate reference surface, probably not straight either. There is a clearance of about 3mm between the rack and the channel. You could be spending a lot of time to fill that gap with shims of varying heights. Properly applied d/sided tape has become accepted in the metal engineering industry for "structural" use. On the MechMate, even the d/sided tape is an overkill because the stresses on the long racks are very low. The end-screws are enough to hold the racks, the tape is only to stop the racks from sagging under their own weight. (Those semi-trailer trucks without all the old-fashioned rivets showing, are sometimes held together with d/sided tapes.)   Bill McGuire Registered Username: Johnnydoughey Post Number: 13 Registered: 12-2006 Posted on Friday, March 16, 2007 - 06:17 am:        Actually, my thought was that there would be some flex in the rack (pressing the tape together) as the pinion gear travelled back and forth, shortening the racks lifespan and adding wear to the gears... although the tape may be fully compressed after just a few passes... in which case, the problem is a moot point. Just a thought. Thanks for the input...   Gerald_D Registered Username: Gerald_d Post Number: 1155 Registered: 11-2005 Posted on Friday, March 16, 2007 - 06:51 am:        I don't think the compression of the tape is a factor at all. The pinion force is relatively low, the 16mm [1/2"] square rack is fairly stiff and the tape area is big. I did some measurements while experimenting with backlash in a non-springloaded pinion system and didn't detect any tape compression at that time.   phil bizley Registered Username: Dumpty Post Number: 4 Registered: 01-2007 Posted on Wednesday, March 28, 2007 - 08:23 pm:        Gerald, i have got my racks from www.stdsteel.com and thought they would be module 1. I had purchased mod 1 pinions here in the UK.but they are wrong size. i sent an email to Tim at standard steel asking him what module he had sent me and this is what he said ( Your racks are 20 diametral pitch. That is equivalent to a 1.27 modular. Pressure angle is 20 degrees.)so what i need to no is what do i ask for when ordering the pinions.Phil   Gerald_D Registered Username: Gerald_d Post Number: 1183 Registered: 11-2005 Posted on Wednesday, March 28, 2007 - 08:39 pm:        That is an unpleasant surprise They sent you inch-based racks while you have millimeter-based pinions. You need to find an "Olde English" style gear now - the stuff that was freely available in the UK before it metricated. The three key parameters are: a. "20 diametral pitch" or "20 DP" for short b. Pressure angle 20 degrees, or "20o PA" for short c. Number of teeth probably 20. Sometimes "Z=20" The fact that a "20" appears in each of those 3 parameters is pure coincidence - they have nothing to do with each other. Your pinion supplier should have no trouble identifying the 20 DP because it is commonly needed for spare parts for older UK machinery. A possible snag is that most of the Olde English was 14.5 degree pressure angle, but it is important to match the pressure angles correctly. Hopefully your racks are 1/2" [12.7mm] wide? There is some 3/8" stuff floating around, but this is slightly too light.   Gerald_D Registered Username: Gerald_d Post Number: 1184 Registered: 11-2005 Posted on Wednesday, March 28, 2007 - 08:47 pm:        Muffet Gears of Tunbridge Wells, Kent have the right spec for 1/2" wide (catalog page). That was my first google hit - there must be quite a few more UK suppliers. Davall of Hatfield, Hertfordshire have the 3/8" wide (catalog page)   phil bizley Registered Username: Dumpty Post Number: 5 Registered: 01-2007 Posted on Wednesday, March 28, 2007 - 09:19 pm:        Thanks for the info Gerald.yes mine are 1/2".I will get intouch with them tomorrow. Should i go for 20 teeth. Phil   Gerald_D Registered Username: Gerald_d Post Number: 1185 Registered: 11-2005 Posted on Wednesday, March 28, 2007 - 09:27 pm:        20 teeth is a popular choice because it is the smallest gear possible on a 1/2" shaft. It gives you the highest resolution (steps per inch). However, if you have high'ish ratio gearbox on the motor (more than 5:1) then you can make the pinion a bit bigger to give a smoother engagement and longer life. Doc Tanner is very happy with his Z=30 pinions on 7.2:1 gearboxes.   phil bizley Registered Username: Dumpty Post Number: 6 Registered: 01-2007 Posted on Wednesday, March 28, 2007 - 09:48 pm:        i was hoping to go direct drive.is that ok with the 20 teeth pinion.   Gerald_D Registered Username: Gerald_d Post Number: 1186 Registered: 11-2005 Posted on Thursday, March 29, 2007 - 07:00 am:        Yes, 20 teeth (Z=20) is the most practical for direct drive. In German, a tooth is a Zahn, a dentist is a Zahnarts. This is where the Z comes from. (All nouns are capitalized in German)   fabrica Registered Username: Daya Post Number: 334 Registered: 10-2006 Posted on Monday, May 14, 2007 - 04:21 am:        Gerald, For my earlier mechmate I ordered the racks from boston Gear the order number was 12760. Last week when my friend in U.S.A made a inquiry for another set of racks and they have said that they no longer carry this item in stock. What other options are availale for us. I would prefer to buy from U.S.A. Manufacturer so that I could get the whole lot shipped in one set.   Gerald_D Registered Username: Gerald_d Post Number: 1348 Registered: 11-2005 Posted on Monday, May 14, 2007 - 10:21 am:        Part no. 12760 still appears in their catalogue (page 35). There is also a 4ft long version of that rack under part number 12758. If you read through this thread, there are quite a few other suppliers mentioned.   fabrica Registered Username: Daya Post Number: 335 Registered: 10-2006 Posted on Monday, May 14, 2007 - 12:38 pm:        Thanks Gerald, I will see weather 12758 is available with them.