Another DIY 2x72''

[Bad_Rockk]

Hi folks,

it's been a while since i posted the start of my first knife build half a year ago. Since then other projects crashed in and so I had to build a shed and a pool deck to please the family needs.

The knife is still not done yet because I got really annoyed by my 3x20'' belt grinder. The belts I have in stock are for woodworking and wear out in seconds when i put some metal against them. And investing in proper belts for this machine wasn't an option. So I stopped working on the knife before I messed it up.

I don't claim this to be my own design. I took as much as I could from other guys and tried to adopt it to my needs. I'm not a metal worker and I can't weld. Here are is the design as it should look like in the end. The grinder will be powered by a 3 HP, 2860 rpm, 3 phase motor that is just 1 year younger than me. I know it will have plenty of power and I have to be very careful with it but I got it cheap. The belt will be driven by a 3x8'' rubber coated drive wheel. Tracking wheel is a crowned 3''.  The flat platten is based on the one of Brian from Houseworks but with a 4'' contact wheel on the bottom and a 2'' contact wheel on the top. The wilting work rest is also adopted from Brian. The tracking is a mixture of Brians design and the design of Beck's Armory. The belt tension is applied by a torsion spring like Jeremy Schmidt did it in his gen 1 grinder.

The plate steel (12mm ~ 1/2'') arrived last week and the drawings are printed to be clued to the plate to start cutting. The tubes are 50x50x5 mm (~2x2x1/4'').

I will do this build with the machines I've already own: a vertical band saw, angle grinder, drill press and files. I know it won't be a perfectly machined grinder, but it will be made by myself. 

So my question is: Does some of the experienced grinder users see any major problems that I have overlooked?

Greetings from Germany,

Tim

[ThomasPowers]

Perhaps a belt guard on the "yank" handle?

[Bad_Rockk]

Hi Thomas,

I changed the handle to be pointing horizontal towards the left grinder side. So the hand position moves away from the belt.

[ThomasPowers]

Ok, an easy fix.

Another question: is your tracking adjuster a positive adjustment in either direction?  I've seen some where the adjustment was dealt with by the handle in one direction but you had to tap the arm to go the other way.  My Bader has a positive direction in either direction and I much prefer that!

[Bad_Rockk]

Hi Thomas,

the tracking can be adjusted in both directions. I will glue in a threaded rod to the star handle, the black ring will be clamped on the thread rod to fix the position. The joint eye also has a internal threat so when the handle will be turned the joint eye moves forwards or backwards. The pivot point of the tracking will use a shoulder bolt. 

As far as I knew this axis does not need regular adjustments. So once it is aligned properly I will tighten it down that the position is fixed.

Yesterday I started cutting my plate steel and recognized quickly that I have underpowered tools.  The base plate was a cut with ~12'' length and nearly killed my little 5'' angle grinder. It took a lot of time and the angle grinder got seriously hot. The next cuts I made an the vertikal band saw (designed for cutting wood but equipped with a metal cutting saw band) but the same here. It takes for ever to cut these thick steel plates. Today I will try to use my reciprocating saw with the stock blades. If this works decent I will order some good blades.

[Bad_Rockk]

I changed my mind after the first try with the reciprocating saw. It also has just 500W and I think a better blade would not make a big impact. Due to that I pulled out our big 9'' angle grinder (probably as old as I am) and ordered some metal cutting disks. It has 1400W and I think is powerful enough to get the job done. This tool is a beast and I have respect to use it. But one big advantage is that we have a stand for it. I can bolt that stand to our workbench and also clamp down the steel plates. 

[Frosty]

A wood bandsaw is more likely to burn up cutting steel, no matter what blade you put on it. If the reciprocating saw won't cut you're hogging it too hard and almost certainly using too fine a blade.

Putting too much pressure on the tool is why they your little disk grinder over heated, maybe burned up. None of this is a machine's fault. You should have someone cut the plate for you or learn to use a hack saw with the blade rotated 90*.

If you're going to switch to a more powerful disk grinder and cut off blades be sure to wear extra heavy duty protective gear and maybe have someone standing away from you so they can call emergency services. If you try hogging even a 7" cut off disk it could EASILY embed pieces of shattered cut off disk in your skull. Maybe even penetrate to your brain.

With all due respect I HIGHLY recommend you pay to have it professionally cut. Just because you have free medical does NOT mean you should risk using it as often as possible.

Frosty The Lucky.

[Irondragon Forge ClayWorks]

I don't know what that link is supposed to be, but there is nothing there.

[Bad_Rockk]

Hi Frosty,

Thanks for your analysis. Maybe I put too much pressure on the angle grinder but not on purpose.

The reciprocating saw try was surely wrong. It is not supposed to cut such thick steel plates and I tried it even tough. So clearly my fault.

I will do the cuts with my father around. I don't want to risk my health but this is also not an extremely dangerous job to do if you do it right.

After I watched several safety videos I checked on the dates on the cutting disks... Well now there is none left. Some of them were "made in West Germany" so 30+ years old. 

Fr some cuts I could use the hacksaw but not for all.

 

[Bad_Rockk]

Today we made the first cuts but without the stand. The stand is ok for cutting brick or other construction stuff but not for this task.

We are doing it slow and as safe as possible. Now I have some file work to do 

[Frosty]

You got it, GOOD! I'm not a fan of cut off disks, even on a good day they can injure you. Good safety gear is a must, I've had too many grinding disks come apart in use. It turned out other non-metal guys in the drill shop just dropped the disk grinder so you could never trust the disk to be sound. I started taking the disk off the grinder and locking them up, with my lathe cutters and good drill bits. <sigh>

I'm looking forward to seeing your belt grinder. Send us a pic once in a while please.

Frosty The Lucky. 

[Bad_Rockk]

Hi Frosty,

1 hour ago, Frosty said:

I'm not a fan of cut off disks, even on a good day they can injure you.

me and my father are the same opinion. It's just our only option so far. So I ordered the carbide blade for the reciprocating saw after all. It's just 8€ so we'll try it and if it doesn't work it nothing to anger about.

I'll keep you up to date with the building process. The pieces we cut today are just rough cuts and I will file them to the needed size. As soon as there is something to show I'll take some pictures.

[Frosty]

You have an angle grinder, why not use a grinding disk instead of a file?

I'm not against angle grinders, I must have 5 or 6 from 4 1/2" up to two 9", one a slow start. I'm retired so I don't share my shop with people I don't approve of. 

Frosty The Lucky. 

[Bad_Rockk]

Thank you Frosty! Sometimes you don't see the obvious 

Just ordered some grinding and flapp disks for the 4 1/2'' angle grinder.

[Frosty]

You're welcome, it's my pleasure. Everybody needs the obvious pointed out now and then. A different pair of eyes is usually a good thing.

Frosty The Lucky.

[Bad_Rockk]

The new carbide blade arrived yesterday and today I gave it a try. It worked pretty good. Here's a picture of it:

I think I had a false opinion on how fast those cuts are made. If you take your time you get a good result. I also switched between reciprocating saw and drill press to give the tools some time to cool down. In the workshop it was 95-100°F. There are still a lot of cuts to make and I will spend several hours with it. But I enjoy the time in the workshop and learn something new every session.

Here are the parts that are already rough cut. It's the a side plate, the flat platten and two parts of the stand. Those still need to be cut/grinded/filed and drilled.

The base plate is already finish. It's the bottom side of the plate. The corner holes are for rubber buffers, the inner holes are for mounting the stand.

[Frosty]

1 hour ago, Bad_Rockk said:

I think I had a false opinion on how fast those cuts are made.

Normal normal, I think everybody underestimates how quickly things can be done when we're just getting started. It's all part of the learning curve. 

When I'm using a power tool hard enough it's getting hot I let it rest in front of a fan, they cool off more quickly. 

There's an old saying that is as true as it gets. "Slow and steady wins the race."

Frosty The Lucky.

[Bad_Rockk]

Hi Frosty,

I watched several videos on the carbide saw blades to find out how others use those blades. In some videos they applied the downward pressure with weight plates attached to the saw. They did it to have constant and repeatable pressure to compare different blades. They used 20-30 lb to do that. 

I know a real craftsman won't do so but I like the approach to apply a constant pressure. I just need to find out how much weight to use to get the blade cutting without overloading it. I think this is a good option because I have to make quite long cuts and so I can let the saw make the work and I can focus on a straight cut and lubrication/cooling.

What do you think about that?

[Frosty]

I think stacking weight on a cut off saw is a SURE SIGN of someone who doesn't know what they're doing.

This also illustrates a serious problem with trying to learn a craft by watching online videos. The ONLY qualification someone needs to be a Youtube expert is a camera and internet connection. The vast majority of how to videos on Youtube show how NOT TO DO things and some are downright dangerous.

When I catch someone even touching the head of a cut off saw when it's cutting, they lose permission to use it. If they argue or try to justify the abuse it might become a permanent ban. I'm not talking about the abrasive chop saws, of course. Those are designed to use hand pressure to operate. You still see the unskilled all but doing hand stands trying to make them cut faster. 

Stop looking for shortcuts and learn to use your tools properly. A little knowledge and a lot of practice is the ONLY secret. 

Whatever tool or machine you use it tells you what's happening constantly be it a file, whittling knife or road grader, they all speak clearly. IF you pay attention. Once you start building experience you'll learn a new to you tool's language more quickly.

Frosty The Lucky.

[Bad_Rockk]

Hi Frosty,

I just cut the next part with the reciprocating saw. And I didn't use additional weight. I had doubts about it after thinking about it over night. 

Yes YouTube is a bless and a course. It's hard to find the real experts. But there are a lot of great craftsman sharing their knowledge, too.

On 7/21/2021 at 7:10 PM, Frosty said:

Slow and steady wins the race."

That's what I did. Stoped cutting every 1/2'' and added some cutting oil. It takes time but it works. No shortcuts needed. As you said, hear/feel what the machine tells you and then respond to it.

My father comes in the workshop from time to time smiling about me. He told me to buy the parts laser cut to safe time and effort. But I wanted to make them myself to safe some money and learn new skills. I think I made the right decision.

22 hours ago, Frosty said:

whittling knife

That's also on my to learn list. My grandfather was very talented carver and all the tools are still here. Unfortunately he passed away way to early and couldn't teache me.

[Frosty]

Reciprocating saws blades are dry blades and shed cuttings without help. Oiling them coats the blade and teeth with something the cuttings will stick to and does exactly the opposite of what you want. Cuttings sticking in the kerf and teeth require more force to move the saw blade and increase friction heating, plus if enough builds up can gall the blade jamming it in the kerf and breaking.

Fluid in cutting devices is primarily to clear cuttings so the blade/bit doesn't gall and jam in the cut. Lubrication and cooling aren't the primary function though it's become the common thought. Cutting fluid does all three but the #1 thing it MUST do is clear cuttings. Thick slippery oil jams saws and drill bits with surprising ease where clear plain water does the job provided the hole / cut isn't too deep.

Cutting parts out yourself for the learning experience is a good thing but you could learn more faster cutting less challenging things. Cutting any length of plate with a reciprocating or abrasive saw by hand is a desperation move. Something you do if you have no other choice. You can learn all the important lessons cutting wood, say planks or plywood to make a cabinet or drawers for your grinder's wheels and sanding belts.

A hack saw to cut the tubing, all thread, etc. to build the rest of the grinder is a good move. With a little practice you can cut 2" sq. tubing faster with a hack saw than an abrasive wheel in a 4 1/2" disk grinder. 

Carving wood has basic rules, if you follow them you can teach yourself. It's sad you  didn't get a chance to learn from your Grandfather but there's nothing stopping you from teaching yourself. There are lots of carvers practicing, search out an organization, web sites or ask at the local hardwood store. 

If you pick up the craft your Grandfather will be smiling. 

Frosty The Lucky.

[Bad_Rockk]

Hi Frosty,

like I said I build a shed (10x11x10 ft) and a pool deck (16x21x4 ft) this year. I did hundreds of cuts with the miter saw, table saw and hack saw. And I learned a lot about my machines. But it is something different than a reciprocating saw cutting 1/2'' metal.

I did all the design myself and both projects are looking pretty good for a full time office worker 

7 hours ago, Frosty said:

Cutting any length of plate with a reciprocating or abrasive saw by hand is a desperation move. Something you do if you have no other choice.

Absolutely right, I don't have metall bandsaw to do it. 

And for the cutting oil, I probably make every mistake/miss thought I could do...

 

[Bad_Rockk]

Hi there,

slow and steady I'm making progress. But I had to change my process because I busted the carbide blade somehow. Didn't changed the pressure or something else but somehow on the last cut the blade lost 5-6 tooth. Now I changed to pre-drilling and then cutting with a standard metal blade and it works pretty good.

I finished rough cutting the two raisers, one hinge, the flat platten, the workrest and one part of the tracking.

For the big side plate I got some help from my dad's colleague. He did the big 130 mm / 5'' hole on a mill. He also did one pass on the outside profile of both side plates. So they have the same profile and are looking great.

Greetings!

[Bad_Rockk]

First test assembly. Starts looking like something:

 

Still a lot of work to do but I'm happy with the progress.

[Bad_Rockk]

Hi there,

I finally finished the first assembly of my grinder. 

The motor and drive wheel are running super smooth. Not bad for 30 years old 

Unfortunately I have two problems with the grinder. I'm using a torsion spring to apply the tension on the belt. The spring I bought fits tightly into the square tube. But when I pull down the tracking arm the spring somehow locks itself. I already contacted the manufacturer and ask for an alternative spring that is narrower.

The other problem is the tracking adjustment. Maybe it is due to the not sufficient belt tension. While running the grinder the screw that tilts the tracking wheel unscrews itself. I could not tap both sides of the square tube because my tap drill was too short. Maybe welding a nut on the tracking wheel side could fix the problem.

Also the adjustment reacts super/too fast. Turning 5 degrees moves the belt a lot. Its hard to find the sweet spot.

If you have any suggestions on fixing my problems, I would highly appreciate your help.