Capped rails using standard "BWC" V-track
 

If anyone is interested I have had a very good experience with Superior Bearing.

I have purchased (2) 12' hardend tracks and (2) 7' hardend tracks along with a 2' hardend track for the "z" axis
for $378 (no shipping).

With the bearings, track and shipping I am under $800 US dollars.

Considering that I have haven't had to buy any tools or spend much time, I would have to say that it (hopefully?) will be worth it in the end.

I tried to find a company to make rails and it wasn't working out. Sorry Gerald.

I told Rick at Superior to just give me what I need for the Mechmate and it was done deal. He takes paypal.

That looks like a great price.

We have called a few knife places around here and they want $100 per hour to grind them out. They guess that with setup time that we are looking at $500. They also say that there is not enough carbon in the angle iron for them to harden it after grinding.

So $378 is way less money and is already hardened.

Now, how tall can the angle iron be without being too tall for the motor mounts? It looks to me like the angle iron will still have to be cut lengthwise using any standard sizes.

The standard motor mounts (and end-stop brackets)are for modified angle iron with about a 25mm [1"] tall leg.

Here is a diagram that will help you guys to try and figure out how to mount your rails:


Points to watch for:
- cantilever distance of the V-roller (musn't go too far left)
- the motor pinion gear position on the motor shaft
- mounting location for the rack
- fixing to the main beams of the table or gantry
- space for the fixing screws of the replacement rail

A closer view showing the Y-car clearance and gantry tube (box section) as well:

To make the designer's life easier, here is a dxf of the above, in mm scale. The "standard" rail cap is also shown - remember it needs 6mm [0.25"] fixing screws at 3" centers and probably some shimming as well. . . .

The idea of having hardened rails appeals to me also. But I don't want to have to redesign the entire Mech.

This idea uses no angle stock of any kind. Nothing to grind or machine at all. All that is needed is a drill press, counterbore bit and tap set.

Assuming we can countersink some holes into the Superior rails (Are they too hard for a countersinking bit? Are just the Wear surfaces hardened, or the whole thing?), we can use some flush screws and get the heads out of the way. 2.25" x .5" aluminum stock is standard and is easy to drill and tap.

Things to brainstorm on:

1. Are the motor shafts long enough?
2. Will the loss of 1/4" in height prevent any moving parts from clearing?

Sorry for the lousy pic, no AutoCAD on my woman's laptop!

That's a possibility. Is that alu readily available? price?

Countersink screws could push the rail up if the bevelled countersink is not exactly in the right place. A low head cap screw will be better - McMaster 93070A121 metric 5mm or [92220A162 inch #10] - don't try to fill the hole in the rail with the screw, leave clearance.

The 2.25 x .5" aluminum is $4 or $5 a running foot.

Gerald,

If you are thinking of revising the design using off the shelf materials, might I suggest we simply change the design to incorporate the Superior Bearing rails?

1. $380 is less than any shop is going to charge to grind the rails
2. The rails are hardened (i know they don't "need" to be, but it is a good thing anyway)
3. Everybody is already ordering the V-wheels from Superior, so that is one less vendor to worry about.
4. Even if I had a cheap table saw to sacrifice, I'd rather spend a hour at the drill press than a whole day filling my shop with abrasive dust.

I would be willing to bet 1/2 of us would have a MechMate up and running by now if it was not for grinding those rails.

MetricMetals of Toledo is only an hour from our shop, but the "big" metal supplier around here is Factory Steel:
http://factorysteel.com/ . They claim to ship worldwide. They have an amazing inventory.

$380 might be less than any shop out there might charge, but:
- Those $380 rails are still hanging in space with nothing to attach them to.
- You still have nothing to attach the racks to
- You have not added the shipping charges, nor the 150 screws, screwholes, etc. http://www.mechmate.com/Forum/clipart/happy.gif

Those who do have their MechMates up and running, havn't had huge problems sticking to the drawings. In fact, some of those machines have paid for themselves while others have looked for "better" ways. http://www.mechmate.com/Forum/clipart/happy.gif

The basic design will stay as is because it is the most cost-effective for the DIY crowd, particularly in countries where shopping options are tricky. I might offer some optional drawings in due course.

Thanks for the link to factorysteel.com.

Hello Everyone,

I have just received a partial shipment of hardend rails and let me say that they are perfect.

The bearings fit perfect on top of the rails and there is very little mill mark on the bearing contact surface of the groove.

It appears that they only hardend the top portion of the rail so drilling should not be that bad. I will post some pics later.

Dealing with Superior Bearing has been a great experience.

Gerald,

I would love to just "stick to the drawings", but out of 11 shops I have called to grind those rails, none want to do the job. I ask each shop to give me the number of a shop they think may want an job like mine and they just laugh or moan. One shop told us they thought they could do it for $500, when we called them to get started, it became $500 PER rail! Shopbot wants $1600 for a set. I don't need a "better" way, just a practical way that an average wood shop can get done locally.

If we are having a hard time finding a shop right here in industrial Detroit, it is going to be 10 times harder to get it done in the rest of the land. Vadeem said he could not find a willing shop in highly populated New York.

Your design is ingenious, without a doubt the best on the net. But it is only buildable if one can find a willing, local machine shop. If we can just figure out a way the rails can be made off the shelf, many more people will have access to a MechMate.

I understand the rails need to be mounted to something. So if we stay with an "off the shelf" mentality, unequal angle, in a standard size along with the Superior rails could give us a solution that ANYBODY can do. No grinding, milling or machining, just a drill press. I believe this would require at least an alternate motor mount plate to make up for the deeper rail leg (now at 46mm with the track). Loren says that only the top of the rail is hardened, so maybe we can counterbore the existing holes to get the screw heads out of the way?

James, you make a perfectly logical argument, and I will get around to showing a design for "capped" rails. This new thread is already evidence of that. I realise you guys feel resistance from me, and at the risk of boring you to death, here are the things that mess with my mind....
- V-cap track is flimsy, it needs to be screwed at 3" intervals to a firm, straight backing to give it any strength or accuracy. I think that firm, straight backing might as well be the rail itself.
- Superiorgrinding has made rails at about $130 each for CharlieT, nobody else talks of them. The others are saying $500 per rail which I fully agree is too much. Is Superiorgrinding still in business?
- the thinking that "something I can buy is better than something I can make". The old standard ShopBot rails are cr*p, most of us could do better freehand with an angle grinder, file and oilstone. The off-the-shelf V-Cap track is also unknown (let's see Loren's promised pics)

The other major reason why I havn't leaped to doing the design for V-cap track is simply a lack of information.....

- What material type/size/straightness is readily available to you for forming the base of this V-cap? Is unground hot-rolled angle iron really good enough? I would lean more to extruded alu or cold-drawn steel.

- The V-cap track itself is a bit of an unknown..
Dimension F is not from the shoulder, but I think this is a drawing error on their part. Are the 9/32" holes chamfered to allow for the fillet under the screw head, or must a washer be used between the screw head and the capping?

This might sound like nitpicking, but apparently folk want something better than homemade rails....http://www.mechmate.com/Forum/clipart/happy.gif

My choices of backing or base rail for the T3 V-cap would be:

1. 60x30x5mm cold-drawn unequal angle iron

2. 60x30x5mm hot-rolled unequal angle iron

3. 2.25x0.5 in extruded alu flat bar

4. 2.5x1.5x0.1875 hot-rolled unequal angle iron

5. 2.5x1.5x0.25 hot-rolled unequal angle iron

No.'s 1&3 will be the best technical options, but also quite expensive and not easily accessible (shipping).

No.2 will be better than no.5 technically, because of lower weight, but have the same accessibility problems.

No.5 is probably the most accessible, but technically the worst. (unless it is cut down and ground - that's another thread)

No.4 is slightly better than no.5 on weight and price, but not easily available.

Now I need a couple of voices to tell me your preferences.

I have a possible solution. Why can't the rail have a round edge? Wouldn't round rod work? I use a tool rest on my manual wood lathe that has a piece of drill stem epoxied to the top. I am sure that the amount of impact it take far excededs what a gantry would apply. If the rod would work then all you would have to do is cut the angle iron led to the correct height and epoxy the rod in place. The cut wouldn't have to be accurate or smoth as the epoxy would serve as a gap filler. The hard part would be to get the rod straight along it's entire length, in my case 13'. I belive I have a simple low tech method of doing that but the explation is rather long so I will save it for later.

I have been reading the BishopWisecarver catalogue rather closely. (link - they want your particulars first)

Their standard V-cap rails are not ground - they are "formed" and polished. I would guess the forming is the standard cold-drawn process. Some of their v-cap rails are hardened before polishing.

But, the main reason for studying their catalog was to learn about how they would like us to mount them. Their application notes on page 29 are important when selecting a base rail to screw the cap onto. They emphasise "The flatness, straightness, and parallelism of the plate or bar to which the DualVee® track is attached (bolted) determine the accuracy of the system. Cold finished or extruded bar or plate is adequate for many applications."

Further:

"Greater accuracy is obtained by using a plate or bar that has been ground flat and parallel on the mounting surfaces. To achieve straightness and flatness characteristics to within N grade accuracy levels is fairly routine (± .004 inch; ± 0.10 mm). In fact, accuracies as low as ± .001 inch (± 0.03 mm) have been achieved using carefully prepared mounting surfaces in relatively short stroke applications (1-3 feet; 0.3-1 m). For designs requiring accuracy levels of ±.005 inch and better, mounting surfaces must be prepared straight and flat, and appropriate doweling or reference edge assembly techniques must be employed."

Although the above comes from the BWC catalog, I am sure that the Superiorbearing product is exactly the same, and that the same notes also apply.

Ok, here are a few pics. I will post more if requested or I can email larger files.
Let me know.

I thought the rails were pre-drilled?

That close-up pic; from which direction is it? (I am trying to understand the "scratches")

The drilling of the rails was offered to me as an option for an additional price.
I have chosen to drill them myself since I have a drill press, I will let you know if I have any problems.
I plan on drilling this weekend and will be using 1/4" 20 button head cap screws to fasten the angle iron to allow for clearance issues.


The close-up pic is the flat side (no notch)and the scratches are very superficial.
The scratches showed up as a reflection from the florescent light in my garage.
Those scratches are really nothing.
You can see where the top portion of the rail was heat treated by the dark witess line.

I will post more pics as I continue.

Thanks for all that info Loren. The standard holes/spacing is 9/32" holes at 3" intervals. De-burr or chamfer the hole until the cap-screw head sits down "hard".

What base rail are you planning to screw the rails to? (I want to do a fairly accurate drawing for you)

Hi Gerald,

I haven't thought about the base rail size yet.
I was going to wait for the laser cut parts from Don and attempt a "dry fit" of some sort.
I would greatly appreciate any thoughts and drawings you have on this.
You are the man and brains behind the machine so I will follow your advice to the best of my ability.

I will be using a company called "Industrial Metal Supply" in Irvine California as my source for all metal.

As allways Thank You for your time and efforts.

Superior's web site does say "Comes pre-drilled for ease of assembly", BUT if you clamp them together and drill, I guess you don't have to worry about the holes not lining up.

You might spend $6 on a cobalt drill bit if you have to drill all those holes from scratch. Get a good brand made in USA or UK.

Your local "Industrial Metal Supply" http://imsmetals.com/ has aluminum angle uneqal in 2.5" x 2" x .25" in 25' lengths. you could rip the short leg on any tablesaw down to .75" . The leftover drop could be used inside the Y car rails?

OR

They have aluminum .5" x 2.5" flat bar stock in 12' lengths.

You might call them tomorrow morning and see how much each costs.....

Reckon the aluminum uneqal angle in 2.5" x 2" x .25", ripped in a saw, as James suggests, is a good option. Would everyone be happy to rip alu in a table saw? You won't be getting a precise top face to hook under the shoulder of the V-cap, but I don't think you will see it in the final machine performance. The angle can be drilled with clearance holes.

If you go the flat bar route, the clearance holes need to be in the V-cap rail. Tapping lots of blind holes in alu will be a long job. But the match to the shoulder would be better.

You could do a rough rip with any bandsaw (wood or metal bandsaw will work, set belts for fastest speed, blade with as few teeth per inch as you have on hand) then do a finish rip on the tablesaw (do this if you worry your tablesaw is grossly underpowered).

The finish cut would be very light.

Clean out all of your dust and turn your dust collector off for this job!

I checked some drawings and dimensions tonight. Space can be made for the V-cap rails. Here are the main implications:

Looking at WIDTH (THICKNESS):

10 20 246 D & 10 10 246 D: Reduce 46mm dimension for offset of mounting holes to 43mm.

M1 20 120 A: The area of the ?thin nut? behind the wheel gets down to a nominal 4mm [0.16?]

10 20 400 W: The squareness of the gantry welding becomes more critical. There is less scope for adjusting out the errors.

10 20 440 S: Must be cut precisely to length. Too short : the gantry my collide with the heads of the button head cap screws. Too long : the gear pinions may move off the tip of the motor shafts.

Looking at HEIGHT:

10 20 454 P & 10 30 450 P : These would be the drawings to revise to allow for taller rails. All the motor/spring attachment points need to be moved down. Also the clearance holes for the gearbox screw heads. However, I have allowed for a range of pinion diameters, and if your pinions are small you can live with a higher rail. If you already have your laser cuttings, then I suggest you use what you have and do a complete assembly first. At worst, you have to get 3 new motor plates M5 10 312(modified).

10 20 454 D & 10 30 450 D: If the profiles are changed to move the holes down, then the 10mm swivel point hole also needs countersinking. The right hole for the spring anchor needs threading.

M5 10 100 A: Item 5 becomes a countersunk screw. Item 12 won?t be able to have a nut on its tip ? it will have to be threaded into 10 20 454 D & 10 30 450 D.

10 10 248 & 10 20 248: The stopblocks must become taller. (They may get in the way of some screws holding the rail caps on)

The button head cap-screw is a very good choice as it is still inside the overall wheel width - the wheel will foul before the screwheads. Suggest that the rails are clamped together for the drilling, and then separate the rails and increase the holes in the base rail to 5/16"

The V-cap track has a slight fillet in the corner in for the location shoulder - make sure that the base track has a slight bevel to clear the fillet.

In the next release of the drawings, there will be provision for fitting 6 rollers to the z-slide's spider. This will allow the z-slide to be pulled 60mm [2.4"] higher up before it falls right out of the rollers. In fact, it will fall out of the lowest pair of rollers but will still be held in position by another pair of rollers placed 60mm higher. This mod was made for people who want to load very tall workpieces, and who have long/deep cutters to draw out of the workpiece. If you do plan to do such deep work, you will want to purchase:
14 off Guide Wheels GW3 wheels (instead of the standard 12 off)
6 off Eccentric Bushings B3X (replaces part M1 20 210 T) (instead of the standard 4 off)

Hello Gerald

When do you think the the next release of the drawings will be?

Thanks

A couple of daysweeks.

I am in the process of mocking up one set of these made rails as a "proof of concept" model in the very near future. I have attached a picture of what I intend to do for economy. The angle shown is 2.5x2.5x.25 Architectual alum angle with the short leg ripped on the table saw to 23/32" to match the rabbet/shoulder height of the T3 cap rail. Price for the test. 35$ for 25' of angle and 60$ for cap rail...if all goes well, I will have a hardened rail system for about 100$ each side.

Wish me luck!
Sean

Sean, I was playing with exactly that last night!

There are some problems with that layout: The rack is going to sit partly under the alu, and partly under the V-Cap, if one wants the pinion to sit mostly on the motor shaft. Remember that the shaft of the geared motor is 5mm [3/16"] shorter that that of the ungeared motor.

But, if we accept that the height of the V-rail will be 30mm [1.25"] in future (I think that is a given now), a neat solution could follow. Now we can mount the V-Cap on the inner face of the alu angle. (mirror the cap over and lift it up 6mm [.25"]. That should solve a lot of issues . . . . .
Well, that was 11pm last night and is on my home computer, so I can't pop the sketch here now. Any comment on that?

(The alu base for the V-rail will still need to have the end-stops welded on, or something bigger bolted on)

Gerald,
Thank you for the quick reply. As you mentioned...I did NOT remember that the pinion gear was shorter. Now you have me wondering if Berg and Sterling Drive Products has a longer gear or at least gear stock that I can bore to the proper DIA for the concept test only. Of course, there is the overhung load change on that change. I bet it would be safer for me to wait to see what you come up with. If you mirror the placement, will I need to drill and tap the cap rail and still put the button heads in from the outside looking in? I am worried about the clearance on the gantry. Or am I being over zealous?

The end stop issue I have resolved....I can either weld or bolt on a modified stop, which I am in favor of doing.

One quick note on Alum to steel connection for the forum. Anytime alum meets steel (ferrous metals) there must be a barrier material (paint, UHMW tape, something) between the two to minimize oxidation and reaction to each other. I have planned to add 1/32" barrier film between the two on final assembly if this works. The stainless steel bearing will not be an issue. Additionally, since you have an independent ground wire running to the controller from each individual axis, I am not worried about maintaining a "rolling electrical ground"

If any part of this seems strange, mechanically wrong, or just "doesn't seem right" - please advise. I haven't built a machine from scratch since my graduate school days in machine automation.

Best Regards,
Sean

Sean, can you work with .dxf files for CAD?

4 posts merged into 1:

Hi Sean,

I have a very hard time seeing the details in the picture.

can you enlarge them ?

As a side note, have you considered using cold rolled steel instead of aluminum ?

I worked with a guy ( I think it was Turkey) who said he could get any steel he wanted, but aluminum was soooo expensive that it was not something he could afford.

Also, cold rolled steel is pretty decent in size dimensionally, and since you are not machining it, just drilling it, it might be an alternative.

is there a place on here one can post .dxf files or dwg files ?

here is yet another possibility.


a second block


the Superior Bearing size 3 rail has a 1/4" (6mm) rise above the block.
that means a pair of 1/2" blocks as shown in my last post would put the angle at the same height and same location as one would do now with grinding an angle iron part.


It looks like a second way to get the same thing. of course I do not know what other things might interfere with the second block.

Dave

Sean, here are my dressed up doodles:

The white motor shafts shown are the shorter 32mm shafts from the geared motors:








So, the result is that the rail drawing M1 10 110 M has been changed to show an overall height of 28mm [1.1"] to make the JR Skated rails interchangeable with the BWC/Superior rails resting on 6mm [1/4"] strip/extrusion.

Gerald,
Any format is fine. I draft in AutoCAd daily - thru release 2008. Dwg or Dxf fine. I appreciate the quick reply and hard work.

A side note: Donald was kind enough to sell me his last set of Laser cut parts, therefore, I am certain I will have a couple of modifications to do to the motor plates. Nothing a quick plug weld and redrill won't fix! :)

Thank you.
Sean

Dave,
I can use steel and have access to all the tools to deal with it. I was just keen to using the Architectual alum angle due to the nice crisp (and almost always) straight 90 deg flange to wall alignment. Not to mention drilling and cutting the leg down to size is easy! Gerald has been kind to quickly update the dwg files and show the pros/cons of the arrangement we have been talking about for days now. I think now Gerald has a nice "universal" change to his machine design to work with most everyone depending availability of iron, alum or JR's Skate grinder.

Regards,
Sean

Seems that there is a path for everyone. Those who want to grind their own, and those who want to use pre-fabricated.

I can see that Gerald covered the two main points he was worried about. the big one was getting the motor shaft directly under the full gear rack.

the second (minor one) was that the rack was on only one piece.

Dave

. . . . there is a third one . . . .

That the rail locates to extruded, and not sawn surfaces.

. . . . a very important third one that has been eluding me until waiting in the car for wife to get the Thai takeaway meal last night. :)