MechMate CNC Router Forum

Go Back   MechMate CNC Router Forum > Archives
Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Closed Thread
 
Thread Tools
  #1  
Old Fri 13 April 2007, 11:48
Gerald_D
Just call me:
 
Handmade V-Rails using a baby 4.5" angle grinder - moving rails over grinder


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.

  #2  
Old Fri 13 April 2007, 12:03
Gerald_D
Just call me:
 
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
  #3  
Old Fri 13 April 2007, 12:15
Marc Shlaes
Just call me:
 
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??
  #4  
Old Fri 13 April 2007, 12:23
Gerald_D
Just call me:
 
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.
  #5  
Old Fri 13 April 2007, 12:29
Manjeet Singh
Just call me:
 
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")
  #6  
Old Fri 13 April 2007, 12:37
Marc Shlaes
Just call me:
 
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!
  #7  
Old Fri 13 April 2007, 14:27
DocTanner
Just call me:
 
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
  #8  
Old Fri 13 April 2007, 16:58
Paco
Just call me:
 
Indeed, very clever!

I can't wait to see the 45 deg. tests.
  #9  
Old Sat 14 April 2007, 01:01
Gerald_D
Just call me:
 
I can't wait either Paco!
  #10  
Old Sat 14 April 2007, 08:17
Gerald_D
Just call me:
 

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.

  #11  
Old Sat 14 April 2007, 09:22
Paco
Just call me:
 
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.
  #12  
Old Sat 14 April 2007, 09:55
DocTanner
Just call me:
 
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
  #13  
Old Sat 14 April 2007, 10:38
Gerald_D
Just call me:
 
"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!
  #14  
Old Sun 15 April 2007, 03:46
Gerald_D
Just call me:
 
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!
  #15  
Old Sun 15 April 2007, 04:33
Gerald_D
Just call me:
 
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.
  #16  
Old Mon 16 April 2007, 09:55
Greg J
Just call me:
 
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.
  #17  
Old Mon 16 April 2007, 10:33
Paco
Just call me:
 
Yes, pretty inspiring!

Tinkering some metal projects myself, I can always some creative ideas like this one.
  #18  
Old Mon 16 April 2007, 14:32
Håvard
Just call me:
 
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...
  #19  
Old Mon 16 April 2007, 19:28
Jay Waters
Just call me:
 
Absolutely ingenious!! I love the solution to the idea. Really achieves a very good finish on the rails. Very impressive.
  #20  
Old Mon 16 April 2007, 23:02
Gerald_D
Just call me:
 
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)

At this point JR Hatcher made a post which has started a thread all on its own here
  #21  
Old Thu 26 April 2007, 06:30
Greg J
Just call me:
 
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.
  #22  
Old Sun 20 May 2007, 06:35
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Progress, or lack of

In my last post, I said I would upload some pictures and update progress. That was almost one month ago. Things have been extremely busy with the day job and have not had any time for the fun projects

I've got one side of the V done, and one of these days will finish the other side and post pictures. Gerald's baby grinder does work very nice, just takes time.

Greg
  #23  
Old Wed 26 September 2007, 21:39
ldorta
Just call me: Leandro
 
Curitiba (PR)
Brazil
Hi Folks,
I'm in doubt. Should this "V" be hardened?
How is it done? I asked some companies that makes this kind of jobs here in Brazil, but them told me that it´s not possible to treat this kind of iron. Is that true?
  #24  
Old Wed 26 September 2007, 22:46
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
This V is not hardened. It is true that "angle iron" cannot be hardened. There are no problems with "soft" rails. If you are worried about it then use soft wheels to protect the rail. We have tested hard wheels on this soft rail and also soft wheels - none of them show a problem. The Size 3 wheel is wide and has a big diameter - it is gentle on the rail, and that is the reason we can use "soft" rails. Bite some "soft" angle iron with your teeth - you will discover it is already quite hard.
Closed Thread

Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 06:43.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.