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Wayne Cordrey
Registered
Username: Waynec
Post Number: 4
Registered: 07-2006
| | Posted on Friday, August 11, 2006 - 04:36 am: | 
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I'm considering upgrading the rails on my PR with HiWin linear rails and blocks. I plan to mount the linear rails on the top surface of my existing unistrut X rails. I'll be building a new gantry, and will put Y axis linear rails on new HSS retangular tubes. I plan to use 25mm Hiwns on the X axis, and 20mm on the Y axis gantry.
Anyone here have any experience installing this kind of rail?
My key question is about the requirements for accuracy. I understand the HiWin rails and blocks will be really tight tolerances. Will this present installation problems for me?
By that I mean, will these tight tolerances of the rail and block cause the gantry to bind if I have imperfections in the installation of my X or Y linear guides?
I plan to use tensioned piano wire as a guide, and use a battery and flashlight bulb as an indicator when I'm just making contact. That can get me pretty close, but I'm wondering if that is close enough?
I can fall back to BWC rails, but I'd like to take the step to HiWIn rails if I can get the installed with my skill level and equipment.
Any help would be appreciated. I've got about a week to decide on HiWin or some variation of the BWC wheels/rails system.
Wayne from White Salmon |
Ken Zill
Registered
Username: Kenz
Post Number: 1
Registered: 07-2006
| | Posted on Friday, August 11, 2006 - 08:56 pm: |
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Hi Wayne,
Sorry I can't help you with experience with the HiWin rails.
But they look interesting and I was wondering what model of HiWin linear rails you were thinking of using and how much they cost.
—Ken |
Wayne Cordrey
Registered
Username: Waynec
Post Number: 5
Registered: 07-2006
| | Posted on Saturday, August 12, 2006 - 07:14 am: |
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Automation4Less.com shows HiWIn rails and blocks in various sizes and tolerances. I'm looking at 25mm AGH series rails (width) for the X axis, and 20 mm rails for the Y axis. I'm estimating about $1500 for rails for X and Y axis, includng bearing blocks.
That's alot of money compared to BWC wheels and rails. That's part of why I'm investigating this more. Relative to the cost of a new machine, its not that much, but its sure alot more than the BWC wheels and rails would be. If I can't install the HiWin system well enough to take advantage of the closer tolerances, it doesn't make much sense to spend the extra money.
But after watchng the wheels and rails on my PR, I'm just not convinced that this system can prevent unwanted vertical motion or will be rigid enough under normal forces found during routing.
Still undecided, but the HiWIn rails look better to me. |
ralph hampton
Registered
Username: Rhfurniture
Post Number: 5
Registered: 08-2006
| | Posted on Saturday, August 12, 2006 - 02:07 pm: |
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Wayne,
If it is any help, I am most pleased with the improvement on my prt (benchtop) using (some larger) BWC hardened rails (oil wiped - very important) and wheels. I also have a 2nd stepper driving the car along the gantry, and have abandoned the shopbot hold-downs, using the sprung motors for this - it works very well. |
Wayne Cordrey
Registered
Username: Waynec
Post Number: 6
Registered: 07-2006
| | Posted on Sunday, August 13, 2006 - 07:30 pm: |
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Ralph,
The BWC wheels/rails is very tempting. I'm flipping and flopping on this one. I have a PR, so I won't be using a sprung motor. So my biggest problem is that in my redesign there would be only gravity to hold the gantry to the x axis rails. When I drill, or encounter resistance in a cut, the tendency will be for the gantry to rise out of the cut. Even spring tension won't fix this without causing resistance to axis travel.
But its very possible I'm swatting flys with a beam. If these are not actual problems, then the BWC rails are probably good enough. On my PR now there are too many other variables to determine if I'm getting 'uplift' or Z axis problems from the current setup, let alone from the upgrade I want to do. So your apparent satisfaction with the BWC and your mods has me thinking about saving money for a spindle instead of spending it to solve problems that may exist only in my tiny brain.
Flip flop flip flop.
Wayne from White Salmon |
ralph hampton
Registered
Username: Rhfurniture
Post Number: 6
Registered: 08-2006
| | Posted on Sunday, August 13, 2006 - 09:49 pm: |
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Good luck, whichever way. I hav'nt had a problem with lifting carriage, and some just abandon the hold-downs, which are pretty icky anyway. I can get the bwc rails dead straight by packing where needed - get the pre-drilled variety if poss - and if you want a roller hold-down, you can run it off the bottom of the bwc rail. It's the silky smooth ride that does it for me....
r. |
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