Handmade V-Rails - "JR Skate" has 4.5" grinder riding the rail

[Greg J]

Here's my version of J.R.'s Skate (rail edge grinder).

I used 14 gage for the base plate for two reasons. First, it is easy to work with. There are slotted holes, and I don't have an end mill to machine these features. Instead I used a jig saw with a metal cutting blade. Second, 14 gage plate is what I had laying around the shop.

Because I used the 14 gage, there was allot of flexing. So I added 1/4 inch thick bars for stiffeners. These stiffeners were left overs from cutting the 2-1/2 inch leg of the angle down to 1 inch. Waste not, want not.

The bearings were stock from www.vxb.com. The other parts (handle, nuts, bolts, etc) were McMaster Carr.

I tried to fabricate this tool, so anyone without lathes, end mills, etc. could make one. The cost is resonable also.

skate1.jpg

skate2.jpg

skate3.jpg

[Gerald D]

Ah! The proof of the pudding shall be in the eating!
(Looks good, but let's see if it works.)

If I were making the "JR skate", I would cut off the ends so the tips of the rails would be visible all the way to the rollers. Also, I would trust the handle screwholes in the body of the grinder to actually hold the grinder at the correct angle - can you tighten those hard into the (plastic?) body? I think I would shorten everything as far as possible so as to lose less unground rail length at the ends.

[Greg J]

Yes, it does work fine. I'll post some pic's of the rail when I get time. (My weekend job is irrigating our alfalfa crop, geeez, I don't have enough to do )

It rides the rail very nice and I don't think one needs to cut the ends off to the rollers. The plastic body of the grinder has brass inserts for the handles so it holds the grinding angle OK (not saying it couldn't be better )

Yes, there is some waste on the ends of the angle, approx 10 inches [254 mm]. I have not cut my 20 foot [6 m] angles yet. The waste will equate to about 4 USD [2 USD per foot for 2x2x1/4 inch angle).

Greg

[J.R. Hatcher]

It looks good, I hope it works as good as mine does. S/N 002 has been issued. Who wants S/N 003?

[Greg J]

Not so fast with the S/N. Gerald has a good point. When I post pic's of a good rail, then I'll accept 002.

It may still require some mods / refinements. Something is not ridged. I don't have a consistent surface / edge on the 45 degrees.

[Greg J]

Back to the drawing board. That Dewalt grinder with the plastic housing does flex at the connection points when grinding. How in the *%$# can Gerald see that and he's half a world away and I couldn't.

Learn and move on. I have a Ryobi grinder like the one used in the trash can example of the rail grinder. Its a newer model and the housing is different. I'll try something new with the other grinder or buy another angle grinder that will work.

Lesson learned - make sure your grinder has a metal housing for a solid connection. Time for a beer and a ball game.

Greg

[gmessler]

Hi Greg,

Great job on the skateboard!! What model number bearings did you use?

I spent a lot of time looking for a good grinder to use for my skateboard and have found that most of them have either plastic housings or the handles are no longer perpendicular to the body of the grinder they are angled back. I had previously purchased this one from Harbor Freight but was unsure if I could make the front attach the way Gerald did on his. With your design I don't think it would be and issue.

http://www.harborfreight.com/cpi/cta...emnumber=31309


Hope this helps.

Greg M

[Greg J]

Thanks Greg,

If I can't find a suitable grinder locally (slim to none), I'll order tomorrow night (If I do one more overnight shipping, my wife is gonna shoot me).

The bearings/rollers are P/N - R12ZZ (3/4 inch ID x 1-5/8 inch OD x 7/16 inch wd).

Attached is a partial parts list. Note that I used low head socket cap screws. Not allot of space. I would also go to a larger three-arm knob. The list is not complete, and I'll finish it some day.

Greg

J.R.'s Skate Parts List.pdf

[Gerald D]

If you take a bit of flat bar, say 1" x 1/8" x 4" long, bend the last 1" at 45 degrees, erect that verically under the grinder, then hoseclamp the body of the grinder to that bent 45 deg. . . . . . ? That should attach the grinder at a 3rd point and steady it out.

[Greg J]

Hmmm ... always the simple solution ...

Grinders are so inexpensive these days, I'll look in town tomorrow to see whats available, ....

P.S. - One more "move" on the irrigating tonight and up at 0500 for the last "move" and off to the day job. I must enjoy this

[Gerald D]

Hey, I had to look up alfalfa to figure out what it is. Turned out to be the stuff we call lucerne and of course there is a lot of it here too. Do you feed it to your own animals or do you sell it?

[Greg J]

Good Morning Gerald (as least here),

Both. There are allot of dairies so we sell mostly to them. Our friend has two dairies and 10,000 head of cows.

Oops, getting off subject (sorry). I'll look for an inexpensive angle grinder today or maybe get a flash of genius and figure out a way to use either of the two that I already own.

[Gerald D]

There is a connection between cows, dairies and CNC routers, so by luck we have hit on something that could be very useful to you.........

Holding boards down to CNC tables and auto-milking of cows use vacuum pumps, big vacuum pumps. You might starting lining up an old vacuum pump to fall in your direction . . . . .

[Greg J]

I sure like the way think. I wouldn't have thought of that in a million years.

You also wouldn't believe what people throw away. Rebuilding pumps is right up my alley. I will keep my eyes open for an old vacuum pump.

Thanks and have a good day/evening.
Greg

[Greg J]

Things are looking up. I found an angle grinder with a good metal frame that can be modified. Locally!!! and for 21 USD

Will start the mods tonight. I wonder if there is a self help group for the MechMate/CNC addiction.

[Alan_c]

Good going Greg... I am still working on my design, that problem with holding the angle of the grinder is also concerning me but some lateral thinking will get it sorted.

the best support you are going to get is right here amongst fellow addicts

[J.R. Hatcher]

Greg my main plate is 1/4". If I have any flex in the bearings that ride the sides of the angle I can't tell it. Because your main plate is only a little over 1/16" it seems to me there would be a problem with this type of flexing. I would suggest you check this on a scrap piece of 1/4" material. If these bearings spread any it will cause a problem in the finished rail. Just a thought.

[Greg J]

Thanks J.R.

I don't think its a problem, but, if I've learned nothing else, I have learned that "The proof is in the pudding".

I will take your suggestion and verify. I've got everything needed to modify the skate, but time. Hopefully I'll have some "leisure" time this weekend.

Greg

[Hugo Carradini]

J.R Nice peace of art. Because you are capable of doing such a beauty, I want to ask you if you have seen working . . . . . . . . .

This moved to the thread where milling (not grinding) of the rails is being discussed. link

[J.R. Hatcher]

Hugo I have never seen either of these tools. I think the smaller one could work if some modifications were done. As it is right now I agree with you, it would not cut the inside bevel. When do you plan to start your venture?

[bbreaker]

hugo, if you want i've got this link.

http://www.gullco.com/more_kbm.html

Michel

[J.R. Hatcher]

Go to my thread and you will see how I used the "skate" to grind my rails. However afterwards I realized how simple it would have been to have built the MechMate base then attached the rails as if they were already ground. At this point you will need to leave them extra long. Using the skate you will grind the rails on the machine then remove the extra length. If you choose this way contact me first there are some minor details. If anyone wants close up pictures let me know. J.R. ps I realized I could have the bottom plate laser cut if anyone is interested, possibly even a kit?

[bbreaker]

whooo J.R a kit !!!!!

For me, i jusr need the size of the board, i do the rest, but i've got an idear last night, why not twice the bearings on the long side, you can start right the first time of grind.

Michel

[J.R. Hatcher]

Mickey at first glance I said that is a great idea BUT then I realized the skate has to be turned around to grind the other side.
My base is 1/4" (6mm) X 4" (102mm) X 16" (406mm).
One of the reasons I chose the Hitachi was because it has a 7 amp motor.

[Gerald D]

Originally Posted by J.R. Hatcher

. . . . I realized how simple it would have been to have built the MechMate base then attached the rails as if they were already ground. At this point you will need to leave them extra long. Using the skate you will grind the rails on the machine then remove the extra length. . . . .

All along the plans said to attach and align the rails with extra length.

(I envisaged the "outrigger" running on the opposite side rail . . . . )

[J.R. Hatcher]

Talking about stability. I see Gerald's outrigger being a welded 4" length of 1/2" pipe (w/ a thumb screw mid way[nut welded to pipe]) across the skate plate. Then a 1/2" piece of cold roll (w/ a bearing attached to the end) thru that to the other side. I wish I could draw.

[Gerald D]

JR, now I've got you thinking.

1/2" cold roll to the other side, which is 7 ft away on our x-axis, is a bit light. . . . . . don't rush into this one . . . . . .

My thoughts on "assemble with extra-length" rails have many origins. From the times with our ShopBot and its "too thin" rails, I have been thinking of a "rail-rider" to dress those rails but the rails had no "extra-length". So, I thought one could lay a temporary rail near the original rail and use that to ride on accurately. Maybe an alu extrusion? But the big idea was to have a piece of 30mm [1.25"] cold-roll (there is a "precision" version) as the temp rail. This "rod" supported in adjustable "V-blocks" about 300mm [12"] apart. One would adjust the V-blocks with the help of a dial gauge and the known sag of this rod under its own weight, and turn it under the dial gauges to find its last errors. . . . . . .
For the first rail, one would use the aligned cold-roll rod to give line and height to the real rail being made, while the outrigger which stabilises the twist of the "rail-rider" could happily run on an un-ground rail on the far side. However, as the grinding gets better and better, the outrigger also forces the "parallel", or distance, between the rails. . . . .
These were all schemes which I thought would never be accepted by the MechMate builders because they sound so exotic. Then a bloke called JR Hatcher comes along and shows a "skate" like the darn "rail-rider" that had kept me awake before. I think; "Nice, but everyone else is going to find that too exotic...." However, most think it is great and a couple are being built. Shows how I just cannot predict what the folk here will think is easy or difficult!

[Gerald D]

With JR's permission, I would like to use his ideas and do drawings for a "skate" as part of the total drawing package. A lot of the parts could be laser cut. Only snag is to do it for a grinder that is available across the world. Is the Bosch brand available everywhere? Or Metabo, Makita. These big names are easily available here.

Can guys from around the world please jump into this thread and tell us which grinders are easy to get in their countries?

[J.R. Hatcher]

Gerald you are more than welcome to use or adapt any of my ideas posted to this forum. J.R.

[J.R. Hatcher]

You might want to leave off the entire adjustment thing across the base. Maybe have it slotted but do away with the threaded rods, handles and the angle hanging off the back. It sure did look good it just didn't work very well. The skate exceded my expectations but the adjustments leave somthing to be desired. I have an idea that would raise and lower those top bearings (cam action) to do the same thing with much more accuracy. Off to the shop.