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  #61  
Old Mon 17 March 2008, 10:57
TheDave
Just call me: dave
 
Toledo (Ohio)
United States of America
I'm no professional, but I use my trusty DA sander to smooth sharp edges and remove rust at the same time. I only worry about degreasing if there is a noticable spot after I'm done sanding.

Greg, just my 2 cents, but I would just sand the control box door down and start over. I suck at painting, so matching the spot where I clean off drips is usually harder than repainting.

Last edited by TheDave; Mon 17 March 2008 at 11:00..
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  #62  
Old Sun 04 May 2008, 23:31
Kobus_Joubert
Just call me: Kobus #6
 
Riversdale Western Cape
South Africa
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Moved from another thread:

Thanks, this will be the last drilling on the gantry. At the moment it is outside...to collect some rust before painting. On that note...is painting done with the rails in place or is it better to paint the loose parts by themselves and then assemble it.
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  #63  
Old Sun 04 May 2008, 23:42
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I did loose parts first and then touched up paint after shimmimg and alignment.
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  #64  
Old Mon 05 May 2008, 04:58
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
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I also did loose parts. It works better for me.
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  #65  
Old Mon 05 May 2008, 05:41
Kobus_Joubert
Just call me: Kobus #6
 
Riversdale Western Cape
South Africa
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come on rust
On some of the lasercut parts it looks like the laser process BURN't the oil onto the metal...Hard shiny black surface. Suppose the best is to sand it down with a flapper disk.
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  #66  
Old Wed 14 May 2008, 20:24
DMS
Just call me: Sharma #9 India
 
Rajasthan
India
I am not very much experienced with paints,
Should I us 'Red Oxide' primer paint, which is commonly used here or should I use other specilised primer ?
Also should I apply putty after primer or before primer??

Thanks
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  #67  
Old Thu 15 May 2008, 00:09
javeria
Just call me: Irfan #33
 
Bangalore
India
Hi Sharma,

get it all sand blasted and powder coated.

RGDS
irfan
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  #68  
Old Thu 15 May 2008, 20:53
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
I'm no expert on paint but I will tell you that I used red oxide primer and I applied the putty after the primer.
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  #69  
Old Fri 16 May 2008, 09:27
DMS
Just call me: Sharma #9 India
 
Rajasthan
India
Thanks Doug,
Did you apply another coat of red oxide over putty ?
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  #70  
Old Sun 18 May 2008, 19:05
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Sharma,

No. I probably should have but I was ready to cut so I just painted over the putty. I'm happy with it.

I've been out of town for the past few days and while I was away, I remembered that Gerald recommended against powder coating because he said that it makes it difficult to make changes later. I agree with him. I've made a couple of changes and additions later and it was simple to touch them up with a spray can.
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  #71  
Old Sun 18 May 2008, 19:42
DMS
Just call me: Sharma #9 India
 
Rajasthan
India
Thanks Doug,
I am painting it myself with spray gun I have. Later after shifting and adjustments, retouching will be necessary, then with same remaining paint it will be uniform. So what Gerald suggested is well thought of.
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  #72  
Old Thu 16 July 2009, 13:56
KenC
Just call me: Ken
 
Klang
Malaysia
Mill Scale

If sand blasting is not a piratical implementation, buy rust covered steel; With a thorough wire brush, the mill scale will come off with the rust.

Apply diluted salt solution helps accelerate the rust formation as well. I never tried vinegar, but salt solution is so much cheaper.

This is a common practice in my trade.

Hope this helps.
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  #73  
Old Fri 24 July 2009, 02:29
Claudiu
Just call me: Claus #43
 
Arad
Romania
Rust removal

If you do not have sandblaster by the hand...
We use acid for removing oxides from metal surfaces.
Ex. Use citrus acid diluted for copper.
Ex. Use HCL or Phosphorous acid for steel.

Of course you first remove mechanically all the big stuff.
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  #74  
Old Sat 25 July 2009, 00:55
Jan de Ruyter
Just call me: Jan
 
Pretoria
South Africa
Phosphoric acid (read the label on your favourite soft drink) leaves a coat of phosphate on the steel. Also removes the mill scale, but takes a while. It is better to remove all the big blotches of rust with a wire brush/flap disk. Phosphoric acid doesn't prevent rust from forming but it makes the paint stick better to the steel. Dip/wash steel in acid, wipe with a cloth to remove nibs, paint as soon as dry, otherwise rust will form very quickly. Blemishes can be filled with body putty (raid your wife's vanity cupboard, no just joking!) Lightly sand with 220 water paper between coats to get a good finish.
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  #75  
Old Sat 25 July 2009, 00:59
Jan de Ruyter
Just call me: Jan
 
Pretoria
South Africa
http://en.wikipedia.org/wiki/Phosphoric_acid
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  #76  
Old Wed 30 September 2009, 09:19
chris saintdenis
Just call me: chris
 
detroit, mi
United States of America
I am very impressed with how well this item removes heavy rust. I know most of you have seen these in action but this was my first time using one. Screw it on to an angle grinder and go.

On the Harbor Freight website it shows one mounted onto an angle grinder with no guard. It is typical to not use the guard for this type of brush? No guard, safety glasses, and gloves, is that safe enough? I left my guard "better safe than sorry" but it seems the tool would be more effective with out a guard.
Attached Images
File Type: gif wire brush.gif (24.1 KB, 806 views)
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  #77  
Old Wed 30 September 2009, 09:30
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
Chris, It may be more effective at removing skin without the guard. I think they left it off for the pictures so you could see the product. I always use a guard with mine. I like the skin on my fingers.
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  #78  
Old Wed 30 September 2009, 13:37
ifffff
Just call me: Ivo #38 & #130
 
Parnu
Estonia
Safety glasses are most important with that tool. Skin grows back but eyes dont. I personally know two who had little piece of wire on eye. One hasnt luck and is on one eye blind.
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  #79  
Old Sat 28 November 2009, 14:44
BartDeckers
Just call me: Bart_D
 
Antwerpen
Belgium
My paint system

I would like to share how i will paint my MM.

I used to work as a painting inspector for Hempel Coatings. My job was to visit the shipyards, steel construction and container manufacturers and advise on the correct use of the Hempel paints.

In my opinion Geralds advise in post 2 is right on the spot.

A cheap but good quality and easy way to paint is to use an alkyd paint system and apply the paint with a brush and a paint roller. http://en.wikipedia.org/wiki/Alkyd

It will not give you the smooth finish of spray coated paint or the durability of a gritblasted and powder coated system but it will be more than sufficient to protect your MM from corrosion and it will look good.

Use a brush first to apply the paint in all the difficult to reach areas like corners and recesses, then use the roller to apply the paint on the flat surfaces. Use a round brush and a lacker roller.

Alkyds can have different names like "phtalic ..." and other exotic descriptions but if it says on the can to use white spirit to thin the paint or to clean the brushes than it very likely is an alkyd based paint.

I will use two coats of primer then apply the caulk and then apply one or two coats of topcoat. Each coat not more than about 50 microns in thickness. More paint is not allways better!

Alkyds actually are two component paints, the "curing agent" being oxygen from the air. They will crosslink and form a tough coating. Because alkyds are "oil" based alkyd primers will adhere well to a properly prepared surface.

Don't use alkyds over galvanised surfaces. The paint will turn into a form of "soap" at the contact surface with the metal and will peel off.

Happy building,

Bart
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  #80  
Old Sun 29 November 2009, 03:02
KenC
Just call me: Ken
 
Klang
Malaysia
We have a paint guru in the house!

Alkyd paint, I think they are commonly known as glossy paint. A good option for those (me included) whom doesn't have spray paint facilities. I always has that impression of high paint losses when spraying skeleton structure, and require great length site preparation if one don't wish to see patches of paint all over the place. These are the excuses I can come up with for the moment to delay buying that air compressor in the hardware store 2 blocks away...

It does take lots of patient & skill to produce good hand brush job.

If I remember correctly, except epoxy & Zinc Chromate nothing goes well on galvernised surfaces.
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  #81  
Old Sun 29 November 2009, 14:59
Claudiu
Just call me: Claus #43
 
Arad
Romania
Hey Ken,

I`ve used 2 liters of blue paint and 10% thinner for the whole table. I don`t know if it`s too much or not, I`m not a pro painter. I had also some paint noses hanging from the table due to the fact that light conditions were not so good.
But in the end everything looks fine.

Greetings
Claus
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  #82  
Old Mon 30 November 2009, 07:57
BartDeckers
Just call me: Bart_D
 
Antwerpen
Belgium
Hi Ken,

I would not call myself a guru but i have looked at so many square meters of steel being painted that i got a good knowledge what it takes to get a good paint system.

Like you point out the advantage of using alkyd paint and applying it with a brush and a roller is that you don't need any special equipment or special skills. Spray painting takes some exercise en training, just like welding

Anybody (well you know what i mean) can get a feeling of how to use a brush and a roller.

Last edited by BartDeckers; Mon 30 November 2009 at 08:12..
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  #83  
Old Thu 03 December 2009, 03:12
KenC
Just call me: Ken
 
Klang
Malaysia
Hi Claus, I am trying hard to refrain from adding more toys in my shop...
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  #84  
Old Fri 18 December 2009, 04:30
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Hi all,
To those who knows a thing or two about powder coating, I need some advice sound, experienced please !
Looking at getting some powder coating done for the beast, I know a lot about finishing, preparing & protecting wood, but NADA about steel, worst…. about powder coats.
I read & understand how & with what it’s done, but not enough info to please my doubts & curiosity!

What type of powder should I request for structural steel ; Epoxy, polyester or hybrid of those two ??? ( see this )
Also, for prep the steel, one tells me sand blast is the only way to go, another tell me phosphate cleaning is well enough for steel ( structure or not) indoor usage ( Ie ; our beast ) !
Phosphate cleaning is considerable less expensive, but is it good enough to prep surface ???
I’m concern about some resilient scaling not being removed by this method ( where a light sand blast will ) and only to later increase the chance to loosen the top coat by lack of adhesion !!

Any experienced advice would be well appreciated !
Thanks in advance, Amicalement Robert
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  #85  
Old Fri 18 December 2009, 04:33
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Sorry, forgot this link : See this
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  #86  
Old Fri 18 December 2009, 14:59
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
I believe the worst thing about powder coating is that it is hard to touch up when you get the inevitable garage rash, ding etc. With paint it is easy to touch up and or grind some off, make a mod and then touch up again. I would stick to paint. Cheaper too.
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  #87  
Old Fri 18 December 2009, 20:59
midmod
Just call me: Trent
 
Midland, TX
United States of America
I'm new to this and wanted to know the correct order of events between attaching the rack to the rails and painting and shimming of the rails.
Are the racks painted too?
And do you guys paint the v-rails separate and tape off the area where the racks attach?
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  #88  
Old Fri 18 December 2009, 22:15
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Racks are greased, they don't get painted. The rails are fully painted and the tape attaches to the paint. We first paint the rails, then do shimming/tightentening down then attach racks.
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  #89  
Old Sat 19 December 2009, 22:47
Jan de Ruyter
Just call me: Jan
 
Pretoria
South Africa
Hi Robert,

Sandblasting is one way to go. The problem I found was that it does not reach those hidden places and it is very operator dependent. If the parts are thin and you are using the wrong media, they tend to distort. Pick the media carefully, shot blast is little iron slugs that beat the living daylights out of the steel. We used the stuff to harden torsion bars for some heavy equipment. Sand (carborundum) is very abrasive and can be found in different grades. Soft blasting can be achieved by using nut shells and is typically used on aluminium or soft body panels.

Hydrochloric acid (swimming pool stuff) can be used to strip rust and scale. Simply immerse in the stuff in a diluted form. Always add acid to water and not the other way round. It does not do anything but to remove rust and steel. The item must be rinsed properly to neutralise the acid immediately as it will start to rust in 10 min.

The problem with this acid is that it is highly corrosive and will attack anything near it. So don't use or store it in your garage, everything will have a nice, antique, rusty look.

Sulphuric acid actually penetrates the cracks in the scale and forms little hydrogen bubbles which pops off the scale in the first phase. That is the black stuff you will find at the bottom of your vessel. It then attacks the steel to form a nice clean surface. The longer you leave it, the more it will eat into the steel, forming a nice rough surface for the paint.

Seeing that it is Christmas, you can make your own snow using this method. The by-product of the process is iron sulphate, a nice, flaky, blue, white powder. Just create a saturated solution and put it in the fridge.

Phosphoric acid removes the scale as well, but additionally, it leaves a phosphate layer on top of the steel, which makes the paint stick better, but in itself it gives no protection to the steel. Phosphoric acid is also less aggressive than hydrochloric and sulphuric acid.

My recommendation is to use mechanical means to remove the worst of the scale. A rough steel brush or a flap disk in a grinder provides good results. After that I would use phosphoric acid to prep the steel before painting. Use an etch primer, touch the flaws up with body putty and give a coat of epoxy paint. Hammerite is also a good paint but it is very expensive.

The ultimate test for your paint project is to throw it down a mine shaft.
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  #90  
Old Sun 20 December 2009, 03:56
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Jan….This is GOOD…I like reading this type of info…. I’m drooling….
Thanks a lot for your answer.
Amicalement, Robert
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