CNCzone.com-The Largest Machinist Community on the net!



Home Page Mark Forums Read Today's Posts My Replies Classifieds Reviews Photo Gallery Web Links Share Files Advertise With Us Ad List
Go Back   CNCzone.com-The Largest Machinist Community on the net! > Mechanical Engineering > Linear and Rotary Motion


Linear and Rotary Motion Discuss ball/Acme screws, R&P, linear slides and theory here.


This forum is sponsored by:

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Ban this user!
Old 04-08-2006, 09:09 AM
 
Join Date: May 2005
Location: USA
Posts: 673
Zumba is on a distinguished road
Bronze bushing idea

Thomson linear rods are decently priced from QBC, but the bearings are killer. I'm thinking about using bronze plain bearings.

The main problem with bronze, from what I heard, is that it has a tendency to bind if the rails aren't perfectly aligned. Shouldn't this be pretty easy to solve by using set screws to adjust the angle of the bearings inside the housing blocks?

Also, I'm thinking that I could mount the bearings to the housing blocks rigidly on one rail, and then on the other rail, insert some hard rubber gasket material between the bearing and the block to give it a slight amount of play. Any forseeable problems with this?

Lastly, online metals sells 932 bearing bronze in hollow tubes for a good price. Ends up costing just a few bucks for a 1" ID x 2" bearing. I see other posts referring to sintered/oil impregnated stuff, basically premade bearings. Those cost significantly more. What's the deal?
Reply With Quote

  #2  
Old 04-08-2006, 09:12 AM
*Registered*
 
Join Date: Mar 2006
Location: Boston
Posts: 1,628
lakeside is on a distinguished road

You can get oil impregnate bronze bearing that are self lubricating
Reply With Quote

  #3  
Old 04-08-2006, 09:18 AM
ger21's Avatar
Community Moderator
 
Join Date: Mar 2003
Location: Shelby Twp, MI....USA
Posts: 20,457
ger21 is on a distinguished road
Buy me a Beer?

One problem is that the rails will flex, so the alignment will change as it travels along the "curved" rails.
__________________
Gerry

Mach3 2010 Screenset
http://home.comcast.net/~cncwoodworker/2010.html

(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Reply With Quote

  #4   Ban this user!
Old 04-08-2006, 09:54 AM
 
Join Date: May 2005
Location: USA
Posts: 673
Zumba is on a distinguished road

Hmm.... I plan on using 1" shafting, fully supported along its entire length. Gantry weight will probably be about 50 lbs max. Router would be a Porter Cable. Do you think there will be enough flex to screw with the bearings?
Reply With Quote

  #5  
Old 04-08-2006, 10:18 AM
ger21's Avatar
Community Moderator
 
Join Date: Mar 2003
Location: Shelby Twp, MI....USA
Posts: 20,457
ger21 is on a distinguished road
Buy me a Beer?

How will you a bronze bearing on a supported shaft? Do you plan on cutting away the bottom of it?
__________________
Gerry

Mach3 2010 Screenset
http://home.comcast.net/~cncwoodworker/2010.html

(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Reply With Quote

Sponsored Links
  #6   Ban this user!
Old 04-08-2006, 10:23 AM
 
Join Date: May 2005
Location: USA
Posts: 673
Zumba is on a distinguished road

Yep, open just like an open thomson bearing.
Reply With Quote

  #7  
Old 04-08-2006, 10:52 AM
*Registered*
 
Join Date: Mar 2006
Location: Boston
Posts: 1,628
lakeside is on a distinguished road

you may want to use an undersize bearing as it will have a little spring when spilt also you may want to encase in steel housing to pervent more springing under weight

Last edited by lakeside; 04-08-2006 at 11:21 AM.
Reply With Quote

  #8   Ban this user!
Old 04-14-2006, 04:54 AM
 
Join Date: Dec 2004
Location: Australia
Age: 58
Posts: 410
andy_ck87028 is on a distinguished road

I've put heaps and heaps of thought into this and my entry in this thread might help http://www.cnczone.com/forums/showthread.php?t=19524

I am confident my approach will work in principle. I will be using vesconite as my bushing but irrespective of choice of material (bronze or otherwise) if the bush is absolutely tight to the rod and binding then occurs then alignment is definitely out and to me that is an unacceptable outcome.

I believe my approach ensures good alignment and provides maximum rigidity.

Andy
__________________
Drat, imperfection has finally stopped working!!
Reply With Quote

  #9   Ban this user!
Old 04-14-2006, 05:18 AM
 
Join Date: Feb 2006
Location: USA
Posts: 313
WhiteTiger is on a distinguished road

If you use flanged bushings you can clamp them in place in the split housing with a simple screw mounted end cap. Going with the modest added expense of sintered bronze will also aid in alignment since the 80% compact is far more conformable than solid.


Tiger
Reply With Quote

Reply




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On





All times are GMT -5. The time now is 05:08 PM.





Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2012, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO
Template-Modifications by TMS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361