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  #1  
Old Tue 23 October 2007, 00:57
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
JR's rail grinding skate in a Lasered & Bent format for 4.5" grinders

Here is a proposal to laser cut the original concept of JR's skate . . . . . .

To talk about the skate in general, I don't see the need to have adjustments for both:
- adjusting the top wheel height by eccentrics/levers, as well as
- screws to move the grinder from side-to-side.
One of these methods should be sufficient - my preference is to move the grinder because it is less sensitive and more rigid.

Also, do we really need wheels on top for making one set of rails? Can't the bottom of the skate just rub on top of the rail? How about brass screws up into the bottom of the skate and let the screw heads rub on the rail top? (the grinding throws up a small burr which will chew the brass to some extent, but rather not have a hard "screw" which could wear down the narrowing reference surface on the top of the rail)

Double plastic handles would be a total luxury - I would manage to produce one set of rails without handles, or maybe just one crude steel bar...

Clamping the grinder by only using its handle screw holes would be a non-starter for me - the only rigid place to hold a baby grinder would be directly behind the disk onto the gearbox. With most of these grinders now coming from the East, those screws are likely to be metric. (The Bosch is 4mm)

The four main rollers would logically sit on the same eccentrics that are going to end up on the Z-slide. No need for special eccentrics for the skate. A pair of 6001.2RSR bearings would make a nice roller. Those bearings could be re-used if making your own V-wheels as per M1 20 120.

I am toying with a design and laser cutting for the skate, but I am not yet convinced that everyone can easily find the same Bosch grinder. Also, I don't know if the grind-wheels/disks have the same thickness/offset/depression around the world.
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  #2  
Old Tue 23 October 2007, 12:08
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Right-click and save the attached file to Grinder04.dxf and open with CAD program to see where my thoughts are heading . . . .

Faulty file deleted
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  #3  
Old Tue 23 October 2007, 12:19
gmessler
Just call me: Greg #15
 
Chicago IL
United States of America
That looks Great Gerald!!
What about fine adjustment ability to the 45 angle?
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  #4  
Old Tue 23 October 2007, 12:24
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Shims
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  #5  
Old Tue 23 October 2007, 13:21
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
...okay - That's so simple I love it. Darn your good.
I will let you know how it turns out, I am going to have that made by next week and grind my rails with it.
Sean
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  #6  
Old Wed 24 October 2007, 11:33
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Sean, I look forward to your feedback!

Here is a scheme that incorporates a little angle adjustment - also makes the skate stiffer . . . . .

(Remember to save as a .dxf file)

Faulty file deleted
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  #7  
Old Wed 24 October 2007, 15:10
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Gerald,
I will be glad to update you on the work up. I like today's additions to the skate. I actually added 4 tapped holes to the grinder plate with allen head set screws to add "shimming" adjustment. I like the bolt like outrigger a little better than my set screws.
I also have redrafted the grinder plate to fit my Ryobi AG402 model grinder. It has the same bolt circle as the Bosch, just a slightly larger clearance for the gear head armature. I hope to have a working sample for you by monday. I am out of town the next couple of days, so I will not get back to making the grinder until saturday.
Cheers. Sean
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  #8  
Old Wed 24 October 2007, 23:15
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Just some more to break out of the fixed line of thinking . . . . . .

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  #9  
Old Thu 25 October 2007, 06:40
Dirk
Just call me: Dirk
 
Alpharetta, Georgia
United States of America
Gerald,
On your above illustration, how would you do both sides? It looks like the bearings will hit.
Dirk
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  #10  
Old Thu 25 October 2007, 06:54
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Swop the spacers to the other side after doing the first sides of the rails. (yes, that will involve re-adjusting the eccentrics, but that shouldn't be a problem)

This might be a more stable way of "clamping" to avoid "rocking" - if indeed there is any rocking. I would try this before "outrigger" wheels.
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  #11  
Old Thu 25 October 2007, 07:34
driller
Just call me:
 
Maybe the grinder could be mounted on a shoe that is bolted to the skate.

that would let the skate be fixed, and the grinder could be reversed with just a couple screws.

Dave
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  #12  
Old Tue 06 November 2007, 11:19
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
fun time skating!

I built the Beta version of the skate from Gerald's plans.

DO NOT USE the BETA drawing files if you have them - A few modifications are necessary.

I have to say - it works really well.
I did have to do a few tweaks, but they were minor. Gerald, I will have to send you the dwg file I updated, the hole centers need a little adjusting.

The good.

- easy to fabricate
- Instead of laser cutting, I just printed the dxf file full size and spray glued it to a piece of "COLD" rolled 1/4" plate and worked from it.
- drilled all the holes
- cut along the lines with a band saw.
- after all machining and dressing, I parted the plate on the bend line and then welded back together @ 45 degree angle. Simple, quick...
- Welding hardened the plate which made re-drilling a couple of holes REALLY hard. (I guess I shouldn't have quenched it to be in a hurry
- adjusting nut/rod assembly aft of the grinder is amazing. Super easy to set the grind angle. Bravo.

In the photo's below, I haven't even adjusted the grind angle yet and it's almost dead on perfect from the assembly setup.

The challenges.

- the eccentric bolts from Superior are 12mm - not 1/2" as indicated. Thus, I had a bearing problem that I ordered from VXB. If you order your bearings, make certain that you get 12mm ID - NOT 1/2" To correct this I had to make up a .030 flanged bearing sleeve. Not fun, but not a hurdle either.
- Brass bolts for height adjustment....they wore down after 1 pass and were sticky to move on. Changed to Hardened Stainless Steel.....zippie skippy! Yahoo.....worked like a champ!
- I don't have a bosch grinder like Gerald, but the home depot Ryobi AG402 has the same bolt circle as the bosch. To use the Ryobi, you must enlarge the clearance hole to a slightly larger diameter and add 1/4" standoffs to the frame for the plate to bolt down securely. All in all, easy change.
- have to add a guard. It's really easy to want to grab the grinder body to push with. Glove's and the proper safety gear was a blessing today.

I have 2 really nice handles that will go in the holes just below the adjusting rod. This will keep my hands on centerline. I will post photo's of it with the rail grind later in the week.


The pictures tell the rest of the story.
Attached Images
File Type: jpg skate-overview.JPG (55.1 KB, 10808 views)
File Type: jpg skate-end.JPG (52.7 KB, 9882 views)
File Type: jpg skate-bottom.JPG (53.2 KB, 7616 views)
File Type: jpg skate.jpg (32.0 KB, 7591 views)
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  #13  
Old Tue 06 November 2007, 12:13
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Picture no.3 . . . . . never in my life have I seen such a collection of screws, nuts and washers!
(Wouldn't say this is one of my prettiest designs, but rates high on function.)

Sean, glad to hear we are heading in the right direction. I can't believe I got those hole centers wrong while the ones for the long screws actually worked out

Is there enough space to remove the disk? Somebody will assemble the whole skate before they put the disk on.

The hole can be enlarged for the larger grinder, but I think to leave surplus metal at the back for each user to trim to his own grinder.

Before someone asks, the unused holes in the top pic are for when grinding the height of the rail down......when the grinder is rigged horizontal to the table

The correct bearings for the wheels on the eccentrics are 6001-2RSR
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  #14  
Old Tue 06 November 2007, 14:13
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Gerald,
I have already transfered the hole pattern on the front to the "moving bed" for the cutting down sequence. I knew what they were for the moment I saw them....like the trash can thread you had started a few month's ago!

My craftsmanship on the band saw was a little shaky! I didn't have the correct saw tooth arrangement and I was forced to be a little aggressive in my cuts! That plate looks I had it for lunch

I'll try removing the disk soon and let you know.
This one's a winner. I have added the Bosch layout with the adjusted holes to the laser part list. If you have any further corrections, I will add them too.
Sean
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  #15  
Old Tue 06 November 2007, 16:48
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Took me a while to figure out the reference to "trash can" . . . . . . . aaha! the background of these pics!

A safe(ish) "handle" could be formed by enlarging the upper plate and bending its lip up. I havn't got the feel of the device, so I don't know quite where one has a tendency to grab it.

Hardened stainless screws are a bit exotic for the average DIY guy. Would standard allen cap screws do? (Allen caps are a good bit harder than normal screws).
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  #16  
Old Tue 06 November 2007, 17:28
Marc Shlaes
Just call me: Marc
 
Cleveland, OH
United States of America
Send a message via Skype™ to Marc Shlaes
Sean,

I was also wondering how you held the tool. Looks simple and effective.

Good show Sean and Gerald!
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  #17  
Old Tue 06 November 2007, 18:01
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Could screw a standard handle or two onto some of those protruding threads:
Attached Images
File Type: gif Clipboard01.gif (15.6 KB, 7547 views)
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  #18  
Old Tue 06 November 2007, 18:40
pksharma
Just call me:
 
Sean.
I think the pair of bearings should have a nut in between to keep them apart enougn to hold angle better. This stops tilting of grinder. Also as Gerald said grinder wearing be considered.

PK
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  #19  
Old Tue 06 November 2007, 19:30
Marc Shlaes
Just call me: Marc
 
Cleveland, OH
United States of America
Send a message via Skype™ to Marc Shlaes
PK,

You really can't do that. You will need to make the rail higher and that will change a bunch more parts. I believe (I could go look but I'm in a hurry) that the rail height is 1.125 inches or about 28mm. There is barely clearance for the two bearings. The sample that Sean ran in the picture is prior to cutting the rail down to the correct size. I'm sure that he was testing the tool on "scrap".
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  #20  
Old Tue 06 November 2007, 21:41
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
PK, this design started in these threads:
http://www.mechmate.com/forums/showt...7&postcount=36
http://www.mechmate.com/forums/showt...66&postcount=8

Now that Sean has kindly proved the concept for us, I will try to tidy up the threads a bit.
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  #21  
Old Tue 06 November 2007, 21:49
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
PK - Marc is spot on...the grind profile you see in the picture is on a native 2.5 x 2.5 x .25 angle iron before cutting it down to the required new Beta height of 1.1" tall. As a matter of fact, the 5/16" #3 phillips screws you see in the picture are actually .05" to tall to actually work on the real rail height. I have ordered the correct button head allen screws for the final working model.

Gerald, the SS - 1/2"-13 grade 8 is just something I had on hand in the hardware bin...I am certain anything fairly hard will work. I will try a normal grade 3 zinc tomorrow and let you know how it "feels".

The handles you propose "feel" about the right size and angle. In use, you feel like a lumber jack using a big 2 person BUCK saw....a nice 45 degree grip angle feels pretty nice to "saw" along the angle with. I will snap a pic with the handles attached tomorrow as well.
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  #22  
Old Wed 07 November 2007, 07:43
pksharma
Just call me:
 
Sean,
Please advise me, I have purchased Chinese angle grinder 450W. 10000 rpm with metal body and plastic tail handle. Is it ok for above taper cutting and grinding of angle ? or should I buy costlier one (which is 4times costlier than this)

PK
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  #23  
Old Wed 07 November 2007, 13:29
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Pk,
Based on the limited information on your post I cannot advise you yes or no.
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  #24  
Old Thu 08 November 2007, 03:32
Abdul
Just call me: Abdul
 
Karachi
Pakistan
pk.

I have similar grinder works fine, don't press hard against steel, use its weight only for cutting. One thing about Chinese if they keep working long time they work oterwise they don't work at all or become useless within no time.
Abdul
Attached Images
File Type: jpg Ang_Grinder.JPG (150.3 KB, 7657 views)
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  #25  
Old Sat 05 January 2008, 18:44
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
...a quick note on the Mamba Skate.
- today I cut down all the rails with the top half of the skate.
I attached it to a plywood shoe with 4 bolts sitting up to allow for pitch and yaw correction on the cutting wheel. Worked exceptionally well.
I will post pics next week when I get back in town.
- If you go back to JR's and Gregs posts, you will see a cutting sled example that I worked from.
NOTE: DO NOT try to cut to much at one time. I tried to beat the 5pm clock on friday and got a little agressive on my final pass......Cost me a smoking grinder. Good thing I bought 2 earlier in the season for the MM project!
If I have time, I will start putting the profile on tomorrow, if not, it will be another week before you hear anymore news.

Sean
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  #26  
Old Sun 06 January 2008, 07:09
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Sean,

Whats your rail height?

I never could fabricate a set of rails with my skate. My rail height is 1.00 inch. Finally end up having a friend with an end mill make the X and Y rails. It took him about a month and not the best quality. I wasn't happy with his invoice either.

A real machine shop is fabricating the Z-slide. Should be ready Tues or Weds.
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  #27  
Old Sun 06 January 2008, 07:35
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Greg,
I cut the rails to 1.25" I will now surface grind them to 1.200 flush out any small imperfections in my cutting before I "skate the profile".

Yes, the rails area a little taller than specified on the print, but the swing angle of the motor mounts is adequate for this small adjustment. I will say, it's pretty easy to cut the rails down....it just requires patience. And a spare mini grinder

For those making the MM for the first time, I truly recommend using the 8" channel section as your workbed for the grinding, cutting and such. It makes a really nice "flat" surface to work on.
I know JR referenced this in his build, but I truly believe that using the Channel as a work surface is necessity to getting the deck height correct.
I already built the table at this point, luckily, I had plenty of Large steel laying around in the shop to use as a 20' long workbench.
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  #28  
Old Mon 07 January 2008, 15:05
Digitize
Just call me: Steve
 
Marion
United States of America
Grind Rails

Has anyone considered using a MechMate setup properly with a grinder to make the rails for others in their area? I believe that is what ShopBot did at one time to make the rails for the PRT. With the necessary shims the rail can be leveled properly and the tolorance for the 45 degree angle can be controlled very well. Just a thought....
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  #29  
Old Tue 08 January 2008, 14:51
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Steve,
Funny you mention using the table itself to make the rails...something truly worth trying once I have the first table built.

For those watching from the couch,
I was able to mount the cut rails up on the machine today and starting grinding the profile.

The mamba skate works really well, and at this time appears to have ample clearance with the new 1.125" tall rail section. PLEASE NOTE - my rail right now is 1.25.

Gerald, you asked me weeks ago if you could change the grinding disk once the skate is completely assembled. The answer is no. A small clearance cut must be made in the back of the skate to get the disk to "hop over" the mandrel on the grinder. The bosch might have a slightly shorter shaft and work. My Ryobi is about 1/16" short of making it. A little grinder action fixed the problem. When I have a real life clearance drawing, I will forward it over for you to look at.

On the up side,
I have pictures below to document the progress of the Beta MM Mamba Skate. I have tack welded a fender washer at the end of the rails to keep the skate from falling off. When the rail is complete, I will cut off the rail and that 4.5" of waste will fall off.
By the way, cutting note.
I cut my rails to the following length....
12' 8" and 7' 6".....My angle iron in Florida always comes at least 1" long if not 2"...so I was able to get the rails for a 60" x 120" machine out of 2 lengths of steel.

Back to doing stuff while my wife and I are busy waiting for our new baby girl to arrive.....contractions and working do not go well together. Thank goodness the MM is a good diversion to the waiting game.

Sean
Attached Images
File Type: jpg skate_grind1.jpg (44.5 KB, 7315 views)
File Type: jpg skate_cut.jpg (36.3 KB, 7283 views)
File Type: jpg skate_cut2.jpg (38.4 KB, 7279 views)
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  #30  
Old Thu 10 January 2008, 18:48
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Grinder skate modifications not necessary. I was easily able to get all of the rails ground with one grinder disk. The form factor of the Mamba skate is so small, you have to assemble the 2 halves and mount the disk at the same time. I went ahead and changed the disk for giggles and found that it was REALLY easy to change the disk, re-tighten the skate, and go about grinding again without much readjustment at all.

Total time with the skate to grind (only grind) was about 1.5 hours per rail...not bad. I could have gone quicker, but I chose not to even tempt fate and overheat the surface of the rail or burn up another grinder

Little note on making the skate slide easier....the 1/2-13 UNC bolts for vertical adjustment...it's not reflected in the above picture, but it was necessary to grind a small crown on the end of the bolts to keep the threads from wanting to dig in the rail surface. It only happened when I reached the adjustment part that let the lead of the threads be perpendicular to the rail. A quick grinder wheel action and I was back in business. oh Yeah...the fender washers on the end are a true asset to the grinding step! Easy peezy lemon squeezy.

It's kinda fun being the guinea pig for a BETA part/tool!

I will write a summary of the grinding experience for the future users.


Sean

Last edited by smreish; Thu 10 January 2008 at 18:53..
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