rails
 

Pic 1 shows what was left of the disk for the back rail did not even finished the disk only used that one disk.
pic2 &3 shows rails back to back cut from one side

It looks like you're grinding angles in the middle picture of post 79, how did that work?

Leko,
The picture with the disc horizontal is a illustration of cutting the angle iron down to size, I did cut the angle iron from both sides, that way I found the cutting disc lasted longer, by preventing the cutting disc from slicing through the metal ensures that the disc remain the same thickness and does not grind thinner between the angle iron and the off-cut, the final “flat “grinding was done with a grinding disc. Keep in mind the difference between the use of a cutting and grinding disc.
The picture showing the grinding in action is the actual 45 deg grinding, with a 45 degree conversion to the grinder adaption. I found that discs made by Makita and De Walt is top quality and outlast most other brands.

Disc info
 

Hi guys,

Has anyone ever head, tried or tested SAIT Z-tech (the "Z" is for zirconium grain) cutting wheels ?
How can/do they compare to the preferred PFERD ?
Thanks, Robert ;)

Pferd
 

some updates and trouble
 

. . . . we were trying to cut the angle iron today (see pic in the zipped file, donno why but always the cuts went one mm below as if the cut was digging into the L - angle rail.

May be I did not have a sturdy enough clamp made for the angle grinder.

will try again on monday though - any comments and help are welcome - meanwhile I did not laser cut the grinding attachment - thought would borrow it from vishnu - since vishnu is down with high fever I will be postponing the angle grinding or may be ask sharma to lend his.

will keep all posted though.

RGDS
IRfan

I think you have the wrong grinding technique if your disk is that deep through the metal. . . . .


The idea is to cut a shallow groove over a long distance, come back and cut it a bit deeper, come back again and cut it deeper again, etc. You may take 10 to 20 "steps" or oscillations to get through the metal.

Irfan, I used that method and it did work for me.
Screw your rail against some flat surface,maybe the spoil board and get your friend to hold some safety glases in front of you:(, use both hands on your grinder.Looks like you are holding the grinder down with your right hand on the handle( might be that you are pushing it down.Your clamps look ok I used one of my extractors hose clamps )

Like Gerald`s reply don`t force the cutting disk into the angle iron just, just let the cutting disk touch the metal you will be amazed how much it takes of. Take it from side to side running the full length of the rail. you will do some serious exersise behind the rail but it works.

Look at my thread it should show you.Try putting your rails back to back then you cut them together same hight and they are straight.

Some PICs of progress
 

Here are some PICs of the progress.
I burned the Chicago cheap grinder and had to buy higher amper grinder.
I wanted at least 8A grinder but could not find any that would fit my skate so I end up with the 6A Bosch with a little grinding on the skate to make it fit. I had the older version skate with hole size of 1.72.

Hey, this is all good stuff!

(except for the dead grinder - which is becoming a rite of passage for a typical MM builder)

Kray posted some YouTube videos yesterday.
http://www.youtube.com/watch?v=rraFsgnuh5s
http://www.youtube.com/watch?v=NbhrYvy2wFU

Gerald you are quick I was going to post it here but you beat me to it.
I was trying to figure out what the links was but it was getting late.

It took me about 8 minutes to grind one side of the 10ft rail on the first video. It was getting dark outside and I didn't want to disturb the neighborhood so I stopped and continued the next day.

After grinding those rails, are there any tips you could pass on to the folk that are nervous about doing it?

Good videos and pics!

Thank-you for the compliment.

What work really well for me was using a good grinder and changing out the disk often for faster grinding. Change out the disk once the leading edge of the disk wear out, you will notice the spark will start to spark in the middle of the disk instead of the leading edge. At that moment the disk will glaze and grinding will be slooow. I read in the forum someone mentioned to adjust the front slightly lower than the back to keep the leading edge in contact with rail when that happen but it was more convenience for me just to change out to a new disk. I use two discs for one rail. The first two short rails it took me all day because I was afraid I might push the grinder to hard. I use the back and forward motion but once I got comfortable I just lightly push the grinder forward without the backward motion for about a foot and pause for a couple of second and continue on forward. It seems to grind faster that way. On my last rail in the video my confidence level was really high I just lightly push the grinder forward without stopping and it took me 8 minute to grind down one side of a 10ft of 12ft rail. I stopped in the video because the disk was wearing out and it was getting dark and I didn’t want to disturb the neighborhood. The grinder was really hot when I stopped if I had used one of the cheap Harbor Freight grinder I would of burn it again. If I can do this anybody can too.

I finished cutting the rails yesterday. Light cuts at first, then heavy cuts as was suggested. Worked quite well, along with a few screwdrivers to pry the cutoff away from the rail and prevent binding.

Dust everywhere. But I brushed some of it into a old plastic 1 gal ice cream bucket. The fine grindies nicely show flux lines from a few hard drive magents placed underneath,

Gantry and Y-car rolling
 

I was really hoping to complete more this weekend, But between the freezing rain and loss of electric and now high winds and temps around zero.

Anyway, I hookrd up the generator at the house and one down at the shop. Shop is heated with wood and kerosine(torpedo heater). I managed to get some things done, just slow when it's cold.

I attached rails, welded gantry, and set the y-car. What a great feeling getting the gantry and y-car to roll smoothly. I lucked out and my gantry sat right down on the rails, no adjustment. I took the advise of others and welded it on a tablesaw.

Can't wait to finish the build. It rolls so smooth for being such a big heavy piece of steel. I think I'm a little short on my X cable chain, so I'll have to order more. I also have to get the shielded cables and control enclosure.

Here are a few pictures of the progress.

MIKE

I have finally gotten to the point of grinding the angles on the rails. Took me much longer (and more trips to Lowes and Ace) than I was expecting to get the skate assembled.

Welding nuts for the height adjustment bolts worked great, but I was having trouble spacing the grinder to set the grinding wheel at a good location to engage as much of the bearings as possible without bottoming out on the angle iron's fillet. Finally got it right and zing! bevels a-plenty.

Some things that were definitely helpful:
1. Clean off all the mill-scale. The bearings dont bind up then.
2. A little oil for the height bolt to slide on made movement smoother.
3. Clean up the 45 degree corners with a file so the v-wheel rolls smoothly.

The next most dreaded part of the build was the rail making. Now I know that many of you have said that it is not hard but until you do it yourself you can just not appreciate how easy it actually is. The angle for the x rail that was supplied was not as thick as I requested but decided to use it anyway, mainly because I was sure that the process would not work and I would end up buying linear rails. :eek: Well the process was so easy and went so well that I have a slightly under spec rail but I am sure it will be fine. I have bolted the rail down at centres of 120mm. The reason for this was that is the spacing required for the linear rail that I may have required oh and it adds extra support for the thinner rail :rolleyes:



The rail cutting was very easy and from reading some other posts I think that I may have been very conservative with the rail cutting. I used a total of 4 disks for all the rails. I did use very light cuts and was ever mindful that the angle grinders usually do not survive a Mechmate build. My angle was 2 1/2 inch on both legs so I could not use the whole disk as the skate plate hit the rail before it was totally cut through once the disk wore a bit. If I had used differed rail I may have gotten away with 2 disks I think.

Christmas is underway here in Australia so I will have to go now, I will give an update in a few days when I get time to get back to the machine.

Cheers to all.

Its time to enjoy some food...
Jayson

Yesterday I cut the steel into manageable pieces so I could carry them to my backyard where the workshop is. Good thing I got them off the driveway and inside. It's raining today.


Here's the Mikita Metal Cutting Saw with the jig I made to guide the cut. A little about the saw. It's the Makita 4131. When the discussion about Metal Cutting Saws was raging on the forum and the discussion turned to the Mikita saw, I happened to see it on Amazon for $140 with free shipping. I bought it. I'm afraid it's about twice that now.


I made a wider base. The one it came with was only about 4" wide. I made two guides to attach to the base. The one on the right in the picture is fixed and held with small clamps at 28 mm from the blade. The one on the left has springs between the guide nearest the blade and the fixed piece furthest from the blade. The springs help hold the fixed guide on the right tight against the steel. Good thing I used the springs and not just two fixed guides. The steel width varied nearly 1/8th inch.

The cutting went very well. It only takes about 5 minutes to cut the larger pieces. I cut them at 28.5 mm to allow for clean-up. After cutting them down, I used the belt sander to smooth them. It only took a lite sanding to get them smooth. I only took off less than .25 mm and they were smooth.


I'm sorry these pictures are a little fuzzy. I was trying to show the forum how the Metal Cutting Saw cut. I'm afraid I didn't do too well.

I started the bevel grinding. Here's a picture of the JR grinding skate. You can see that I've added a handle mount. I used the handle that came with the grinder. This grinder doesn't have a top hole for the handle. So, I drilled and tapped a small piece of 3/8's steel to fit the handle. I welded that to another piece that I shaped and drilled to fit on the standard skate. I considered welding it at 45 degrees to the mounting plate, but after trying to see how it would feel, I decided on 90 degrees. It does a good job.


You'll note that I'm using a Skill grinder. My DeWalt was going to require a lot of modification to the standard skate. I found this Skill grinder at Lowes for $29.95. It is almost a perfect fit for the skate. It's 6 amps. I figure if it fails, I can take it back. It's guaranteed for 1 year.:D

Just a note on equipment casualties...I have an older (maybe 10 years) Skill belt sander. It died during the sanding. I really wasn't pushing it. I think it's time had just come. I hope that's my "right of passage" and I don't have to burn up a grinder. Had to finish up with the Porter Cable sander.

Administrative note: I guess there's a limit of 5 photo's per post. I was trying to show 6 (rail after cutting and before sanding) and strange things started happening. That's okay, the photo was kinda fuzzy. If someone is really interested, I'll try to get a better set of photos to show the effectiveness of the saw.

Regards,
John

You learnt a lot from us guinea pigs! I made the mistake of handing the saw and the rails (for 5 big tables) to one of my staff and told him to get on with it. At the end of the day he was wandering off the line. A spring loaded guide would have prevented that.

Update...finished grinding the rails. Whew, that's a job!:eek: Glad it's done! It took roughly 8 hours of grinding. I ground 40' of rail.

First of all, the $29.95 grinder got the job done and is still RUNNING. I had a scare about half way through. I adjusted the bolts to cut deeper and I set the cut too deep. So I was grinding too aggressively. The grinder started to smoke!:( But, it must NOT have "released the Magic Smoke," because it kept working. I let it cool down, reset the depth and worked with the grinder the rest of the day.

Lesson's learned:

1. Don't be too aggressive on the grinding, it smokes grinders.

2. I found that I got the most controlled grinding by letting the grinding wheel PULL the skate along the rail. My job was to prevent the skate from going too fast and thus skipping a part of the grind and holding the grinder down on the rail. When I pushed the skate against the direction of the grinding wheel, I got more aggressive cutting, but it was NOT uniform...and it was HARD WORK! Just be patient and let the grinding wheel do the hard work.:D

3. Also, as someone else already mentioned, by letting the grinder move quickly across the rail, everything stays cooler. Don't rock it back and forth. The grinder stays cooler because it's not working as hard. The rail stays cooler because you're not sitting in one place grinding away. Also, I suspect, but don't know, that since you are moving quickly down the rail, the grinder is constantly encountering and throwing off "cooler" chips and just like in other kinds of cutting, bigger, cooler chips are a good thing.

Question: I noticed after finishing the grinding that a light hand sanding of the ground surfaces removed the grinder marks making the rails look more like they had been "machined." I haven't seen any mention of this idea...at least I don't remember it. Is there a problem with lightly hand sanding the rails? I don't think it would change the dimensions at all.

Regards,
John

The light hand sanding is perfect. We sometimes even drag a file across a rail that is roughly milled (draw filing). Strictly, this does change a dimension somewhere, but by such a tiny amount that you won't notice it. Bolting the rails down makes much bigger changes in the dimensions than a bit of sanding. The smoother the rail, the cleaner it stays.

rail grinding question
 

Hi everyone,
I cut and began grinding my rails this weekend. Would anyone care to advise on the width of the flat on top of the ground V profile? On my first rail I got between .060" to .085" width. Is the width of the flat critical? It looks like the Superior Bearing wheel has a flat about .010" in width between the V flanks and I assume rail flat has to be wider that .010" or it will lose contact with the flanks.
The grinding slowed down after awhile, and I could see that it just wasn't cutting at the same rate, - is that caused by a glazed wheel? Only remedy is a wheel change?
I was unable to locate the Pferd cutting discs anywhere but I did manage to rip 40 feet of angle iron with 4 Tyrolit .045" thick discs. I pulled the offcut back just before cutting through because the kerf was closing and grabbing the wheel.

The Superior Bearing wheel actually has a radiused notch in the root so that it will clear a sharp 90 degree rail without any flat area. (You can test your bearing wheel on a "sharp" piece of iron).

The glazed wheel effect has been mentioned a few times. Simplest solution is to change the disk. To slow the rate at which the glaze forms, tip the skate so that the tip of the disk does most of the work.

Thanks for for the feedback on the Tyrolit disks. Can you give us a type number for that disk?
Catalogue: http://www.tyrolit.com/dataarchive/d..._pk2008_gb.pdf

tyrolit cutting disc
 

Hi Gerald,
thanks for the info on tipping the grinder and the spec on the bearing.
Here's what is printed on the Tyrolit cut off disc:
TA60P-BFXA
STEEL
TYPE NO. 384142
4-1/2, .045 , 7/8"
SECUR EXTRA TOP

cheers
Denis

Thanks Denis. From their catalogue, that is one of their "Premium" disks. Their Standard or Basic disks would probably not perform as well. Just mentioning this so that folk don't grab the first Tyrolit (or Pferd) they see on the shelf without checking the numbers carefully.

Showing my best side- Welding the table
 

We made an honest attempt to cut the rails with the rotary grinder and were not happy with the results. The thin blade tended to "float". Checking tomorrow to see what laser cutting goes for. Any price will be a good price, because we couldn't even cut a straight edge on 3/16ths angle iron.
Undaunted, we moved on to the next item, welding the table w/cross supports, where we had considerably better luck. A 90deg clamp helped immensely in squaring everything up. Now we just have to figure the best way to bolt the table to the X-beams.

Plasma cutting - not the way to go
 

OK, so I call a metal fab shop referred to me by the steel dealer, he quotes me $75 to cut my rails, and I'm thinking, "Bob's my uncle", problem solved. I strap the rails to the top of the Subaru, and trek 40 miles to the middle of nowhere to drop off my angle iron. They've got a nice reception area with all these nice laser cut parts, how hard could it be to cut some rails?
Apparently pretty hard. I told them I was going to be using the edge they cut to run bearings on. They said "no problem." I didn't see a bandsaw or a diamond tipped anything anywhere in their 10,000 sqft shop, which should have been my first clue. On my return 2 hours later I look at my warped, butchered rails and I was speechless. I knew I was in deep kimchee when the owner starts off the conversation with, "this is the problem." I really think I could have done better with a handsaw. I still have hope(although very little change left after this mistake).I'll know if they're salvageable when I take them to the knife grinder to see if he can fix them.
I'm starting to understand why so few MM's have actually been completed. I think I'll drop down and do something like bolt together the skate. Now THAT (I think) I can accomplish.

I think in excess of 25 complete running and cutting Mechmates is not "so few" however, try the skate is has worked for many of us and can produce amazingly accurate results - if one has the patience to spend a few hours it takes to do the job properly. I achieved a maximum variation of 0.2mm (0.008") over the length of my rails which were up to 3m long (118"). No flexing disks or divots throughout the whole process.

Maybe I havn't made it clear enough that one needs to make very light cuts at the beginning, to establish a groove, before piling on the pressure. Under these conditions, I cannot understand why you got "float". Can you maybe think of the reasons it floated?

Gerald and Alan, I agree 100% and would like to add ........

A few suggestions:
1. The finish surface will only be as good as the surface the grinder was sliding on (keep it clean during the process) and how well it was clamped down (C or G clamp every 12").
2. Keep the grinder moving, if the metal gets too hot it glazes the wheel and it will stop removing metal.
3. When the wheel starts to cut through you need to start climb cutting only (saves the wheel)
4. When finished, if you are not satisfied with the surface put a new 1/4"+- thick wheel on the grinder (it won't flex) and make several light runs back and forth across the top until you are satisfied. Note: As you continue with steady pressure on the grinding it will take off the high spots until it's not cutting anything.
5. As you are grinding the 45 degree angles keep both sides equal or about the same all the way down. Leave the flat somewhere between 1 and 1.5 mm.
6. Always wear safety glasses and breathing protection ........... NOW GO MAKES SOME SPARKS.

This is what dirt bikers call a "racer's bend"
 

Alan, you, Gerald, and J.R. are my inspiration. Thanks for all the helpful input. Those tolerances you've achieved are absolutely amazing. I'm going to redouble my efforts and not report back until I have made some forward movement.

Krasch, glad we didn't scare you off! :)

That last banana rail looks usable. If clamps will pull it down flat, the screws at 8" centers will do the same.

I have the same issues with my rails. A little fine tuning required!

A few more photos.
Chewed through lots of Dia 125 x 1 discs, Y axis 1830 and X axis 3800. My angle is 60 x 60 x 8mm thick. I opted for 8mm because it was a much better shape angle that the 6mm version.
I went for a 3 legged angle grinder carriage, tried 4 legs but 3 felt smoother to push around. I`m not sure if anyone has tried pulling the grinder into the cut as I did but I found it easier.
My main X axis beams have 6 pieces of 50 x 5mm flat bar tack welded along the length to stop any resonate vibration.
I have built a concrete feed arm for a Million $$ concrete pipe spinning machine in the past and the 300 Channel arm picked up a nasty vibration and the flat bar fixed that.
Has anyone had issues with vibration or a ringing noise on their MM?

Well a few steps forward. Still have to put the angles on the rails and paint them. My angle iron was 3 x 3 so I made a low tech skate that worked well. Will drill the holes for the prox sensors later as well. More to follow. . . . .

Half way done grinding the rails. That's one nice jig, thanks Gerald.

An update....
 

Got my X & Y Rails done, ran into a little snag with the Y rails but reading in the forum - I found the solution. One rail was .5mm taller than the other, so before I ground the V detail I used a thick grinding wheel to remove the extra .5mm.

THe skate worked awesome, one thing though, I had not even though of - "Its designed for 4.5" grinding disks" I had a stack of 5" disks that I thought I could use, but when grinding the v detail the 5" disk hit the "top of the bottom" of the angle iron before the skate's adjustment bolts hit the rail. I ran out and got the proper disks and it worked like a charm.

I was waiting for the old Bosch to go up in smoke after so much cutting and grinding, but it hung in there. I've had it for about 20 years its cut ceramic tile, biscuit slots, 2 hot rod frame builds. Like a Timex.. What a mess in the garage though, best to do the rail grinding process out side - the weather here did not co-operate though - too cold.

I did notice however that I could "hear" the wheels on the rails, Ifigured that the ground V surface was a little rough so I gave the V profile on the rails a light sanding with some 100 grit sandpaper to polish them up a little and it rolled alot smoother.

My Bosch grinder look just like that....I killed 2 cheap types....gave them back to where I bought it so it did not cost me a cent. I wanted to SPARE my Bosch but in the end finishing my rails with the Bosch...GREAT MACHINE