| Author |
Message |
    
Gerald_D
Registered
Username: Gerald_d
Post Number: 1248
Registered: 11-2005
| | Posted on Friday, April 13, 2007 - 07:48 pm: | 
|
A piece of 30mm [1.25"] MDF with 4 holes, some 6mm [1/4"] "all thread", nuts and washers. MDF about 300 x 700mm [12 x 28"]
Remove 4mm screws from gearhead of grinder - Bosch GWS 9-125 (230V) or Bosch 1810PS (120 Volt)
Screw on a 160 x 60 x 10mm [5.3x2.3x0.3"] steel plate
Attach thin 115mm [4.5"] steel cutting disk. The right disk makes all the difference.
Attach grinder to baseboard. Set disk parallel to board and 25mm above it.
Take it outside and fix to top of dirt bin [trash cart]
Now the grinding starts, and this does need some experience of speed and pressure to get the best results. Constantly move the rail backwards and forwards so that one spot does not get hot. It is NOT like ripping timber in a table saw - it is NOT a sawing process. Lots of steady, even reciprocation needed. The grinder speed can only dip slightly - don't overload it.
Wear eye protection, hearing protection, gloves (for heat & burrs) and old clothes for the sparks
Cut 1m [39.4"] long, 6mm [1/4"] thick angle down in 7 minutes. If I had to do this with longer angle irons, I would want a longer, firmer table and probably another pair of hands.
 |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1249
Registered: 11-2005
| | Posted on Friday, April 13, 2007 - 08:03 pm: |
|
New disk on left - about 2/3's of disk life was used in the 7 minute test:
It wore down from 115mm to 93mm |
Marc Shlaes
Registered
Username: Shlazor
Post Number: 3
Registered: 02-2007
| | Posted on Friday, April 13, 2007 - 08:15 pm: |
|
Fantastic! You are truly unbelievable! My only question is how did you bore the 50mm hole for the gearhead recess? Will a bi-metal hole saw go through that?? |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1250
Registered: 11-2005
| | Posted on Friday, April 13, 2007 - 08:23 pm: |
|
Yes, it was a bi-metal hole saw (44mm) at a very low speed, with coolant water/oil. 125 rpm.
Tomorrow I want to try 45o bevels, but first I want to dress a precise 24mm height.....
I am adding more info to the pics above as I go along, so you might want to read it all again.
Must emphasise the choice of cutting disc - the thin "Pferd" ones mentioned above cut twice as well as any other brand I've ever tried. |
Manjeet Singh
Registered
Username: Manjeet
Post Number: 30
Registered: 11-2006
| | Posted on Friday, April 13, 2007 - 08:29 pm: |
|
Hi Gerald,
fantastic job. I had been thinking to machine the stock on planner but ur idea is great to save time. definately I will slit my angle Iron beforer it goes to machining V on planner.
thanks gerald..
Manjeet
(some more on metal-cutting "planers") |
Marc Shlaes
Registered
Username: Shlazor
Post Number: 4
Registered: 02-2007
| | Posted on Friday, April 13, 2007 - 08:37 pm: |
|
Maybe I am naiave but I wasn't as afraid of the 45 bevelling as the other 'members'. I have conquered weirder things. However, you proved it will be "easy". Thanks much! |
DocTanner
Registered
Username: Doctanner
Post Number: 48
Registered: 11-2006
| | Posted on Friday, April 13, 2007 - 10:27 pm: |
|
Very Clever !!!!
What if a person made a "rollerskate with V-bearings" that held the Gerald's grinder mount on a 45 degree angle.
Using 6" C-channel for skate's rails.
DocTanner |
Paco
Registered
Username: Paco
Post Number: 16
Registered: 02-2007
| | Posted on Saturday, April 14, 2007 - 12:58 am: |
|
Indeed, very clever!
I can't wait to see the 45 deg. tests. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1253
Registered: 11-2005
| | Posted on Saturday, April 14, 2007 - 09:01 am: |
|
I can't wait either Paco!  |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1254
Registered: 11-2005
| | Posted on Saturday, April 14, 2007 - 04:17 pm: |
|
Change to thick, side-grinding disk
Grind cut face flat to 24.5mm. Took 5 minutes plus One can carry on for a long time because you don't really know when you are finished - light sparks are always possible.
Modify jig for 45 degree cuts
Use better mounting screws - 25mm long to hold 10mm thick plate M4
Mount through thick MDF
Set up guide blocks they are too short - must be longer next time
8 minutes later and already cutting too much The two bevels were already touching each other - next time use a finer/slower, less aggressive approach.
 |
Paco
Registered
Username: Paco
Post Number: 17
Registered: 02-2007
| | Posted on Saturday, April 14, 2007 - 05:22 pm: |
|
Look good!
With a 10 feet long rail, as the grinder wheel wear, does the bevel change?
I think I would go with the square one and use it as a seat for an cap on harden rail. |
DocTanner
Registered
Username: Doctanner
Post Number: 49
Registered: 11-2006
| | Posted on Saturday, April 14, 2007 - 05:55 pm: |
|
Excellent proof of concept!
A few hours work and a couple hundred bucks gets 4 rails ready for mounting and an angle grinder left over.
Sometimes you make it way too easy for us!
DocTanner |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1256
Registered: 11-2005
| | Posted on Saturday, April 14, 2007 - 06:38 pm: |
|
"With a 10 feet long rail, as the grinder wheel wear, does the bevel change?"
The shaded, center part of the disk is dished/hollow. If the rail passes across the "dish", then the angle stays perfectly constant and flat. But, that is not so easy to achieve....(the disk is then startind to come very close to the top of the jig - nearly touching the "inside" of the rail) I want to investigate the availability of "cup" disks - those with a narrower flange and a bigger dish.
"I think I would go with the square one and use it as a seat for an cap on harden rail."
A good option.
But there are more options as well:....
a. After cutting down height, take the rails to a knife grinding company. (I understand their biggest problem is the time to cut down the height.
b. After cutting rough bevels, then take it to a knife-grinder for the best price (least work from them)
c. After cutting rough bevels, assemble the MechMate and run it! You might prove that everything works okay, and then fine-tune later if necessary
d. Make some improvements to my cutting process and make nice rails! |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1261
Registered: 11-2005
| | Posted on Sunday, April 15, 2007 - 11:46 am: |
|
Before starting today, the rail was ground down to 23.5mm parallel
Fitted 250mm [10"] long hardwood guide blocks
Borrowed a V-roller and eccentric Please excuse crude bracket - it is Sunday at home
Lightly cleaned/de-scaled the rail and sprayed it liberally with silicon This makes a huge difference!
In the photos below, the rail is just lying the right way up, on top of the grinder. Don't look at the bearing - look at the ground edge to the right.
After re-grinding - the ground edge only has slight scratch marks This rail is the best I have seen compared to ShopBot or those I have made before!
Lightly cleaned with 400 grit paper - It works! |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1262
Registered: 11-2005
| | Posted on Sunday, April 15, 2007 - 12:33 pm: |
|
Have just tried to measure the wear of the face grinding wheel, and I can seriously say that I can't measure any wear. Before starting this rail, I measured the disk thickness at various points and got readings between 6.25 and 6.30 mm. After this 1 meter of rail it still measures in the same range. Obviously there must be some wear, but the disk is difficult to measure.
Knowing that there is little wear of the disk, the strategy can be changed a bit.... Before I was making one pass on left side and then the next pass on the right side, to make sure the V stays in the center. When I realised the disk isn't wearing, I could introduce the roller and finish the left before starting the right.
Before the roller, I could "twist" the rail down onto the disk, or lift it off. The roller can be better in future - possibly more rollers in different places pressing the rail firmly against the guide.
Today I did not chase the clock. You can spend a very long time making sparks and taking off very little metal. The technique is to get an even speed and pressure along the whole length of a rail. NEVER STOP IN ONE PLACE AND MAKE IT HOT. A hot spot can bend the rail and damage the disk. |
Greg J
Registered
Username: New_mexico_woodworker
Post Number: 14
Registered: 03-2007
| | Posted on Monday, April 16, 2007 - 05:55 pm: |
|
Gerald,
You are truely an inspiration. After reading this thread, I've decided not to go to a machine shop to have the rails made. Tonight I will start disassembling my angle grinder. |
Paco
Registered
Username: Paco
Post Number: 18
Registered: 02-2007
| | Posted on Monday, April 16, 2007 - 06:33 pm: |
|
Yes, pretty inspiring!
Tinkering some metal projects myself, I can always some creative ideas like this one. |
Håvard
Registered
Username: Soulvoid
Post Number: 14
Registered: 02-2007
| | Posted on Monday, April 16, 2007 - 10:32 pm: |
|
Hi Gerald,
Looks great!
just out of curiosity, why not set up the wood jig at an angle instead of making two metal jigs? It just seems a lot easier to make one flat metal jig than two, where the other one need welding also... |
Jay Waters
Registered
Username: Mrgadget
Post Number: 27
Registered: 09-2006
| | Posted on Tuesday, April 17, 2007 - 03:28 am: |
|
Absolutely ingenious!! I love the solution to the idea. Really achieves a very good finish on the rails. Very impressive. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1270
Registered: 11-2005
| | Posted on Tuesday, April 17, 2007 - 07:02 am: |
|
Håvard, what I have shown above is just to start some ideas and get people to be creative. I used wood because I was at home where I can work easily with wood. The blue plate was made at my factory in the week before - there we only work with metal.
Okay, the pictures above might make it look too easy and too quick...... For people who are impatient, and who work alone, the results might be frustrating. Two people are going to be needed to push a long rail at an even speed through the grinder - it is very similar to ripping a long board through a table saw. If you try and take too much off in one pass, it just pushes the v-wheel up or stalls the grinder. About 3 roughing passes (setting grinder higher each time) and 3 finishing passes with grinder staying in same position.
The very tips of the rails are not so good because of entering and leaving the roller. Start with rails that are too long and trim the tips off later. (The drawings have always shown 100mm [4"] extra at each end, but more will be better) |
J.R. Hatcher
Registered
Username: Jr_hatcher
Post Number: 2
Registered: 12-2006
| | Posted on Tuesday, April 17, 2007 - 07:23 pm: |
|
Gerald, it's amazing how minds on opposite sides of the world can think in harmony. How do i upload pictures to a post? |
J.R. Hatcher
Registered
Username: Jr_hatcher
Post Number: 4
Registered: 12-2006
| | Posted on Tuesday, April 17, 2007 - 08:03 pm: |
|
Gerald while you were brainstorming this passed week, i was too, here is what i came up with. I will try to upload some pics.
 |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1271
Registered: 11-2005
| | Posted on Tuesday, April 17, 2007 - 08:08 pm: |
|
That's a beauty! Applause! |
Arthur Ransom
Registered
Username: Akransom
Post Number: 38
Registered: 09-2006
| | Posted on Tuesday, April 17, 2007 - 08:55 pm: |
|
JR when I get ready to do my rails how about renting me the grinder for a week. You could start your own rental business! |
Marc Shlaes
Registered
Username: Shlazor
Post Number: 6
Registered: 02-2007
| | Posted on Tuesday, April 17, 2007 - 08:59 pm: |
|
Tremendous! I too would like to rent it!!! That is certainly better than anything I was dreaming about. |
Greg J
Registered
Username: New_mexico_woodworker
Post Number: 15
Registered: 03-2007
| | Posted on Wednesday, April 18, 2007 - 12:06 am: |
|
WOW!! There is allot of talent here.
Very nice work. |
Greg J
Registered
Username: New_mexico_woodworker
Post Number: 16
Registered: 03-2007
| | Posted on Thursday, April 26, 2007 - 02:30 pm: |
|
Here's my latest on using Gerald's grinding method for making the V rails. I made a jig and got one pass on a 10 foot angle. It was getting late and the Dodger's were on XM radio, so only had time for one pass and pictures. I was amazed how well it worked. I will work on it some more tonight and post the pic's. Couldn't have done it without your help Gerald. Thanks. |
Rails & Rollers