Using MDF trim to test CNC programs

[madmachinst]

Have like 7 programs under my belt ( few of em without CAM) and now I have Fusion 360 and I like to play around a lot with the code it generate before cutting so I need to run test parts before going to material ( aluminum steel and even Stainless) is MDF trim board my best and cheapest bet? Anything better than that?

 

[boosted]

There is machinable wax if you are feeling especially timid.

I hate getting wood in my machines. Though I suppose wax is almost as bad…

 

[memphisjed]

Cutting air is pretty cheap. Then so is simulation in fusion.
The feeds for steel would smoke in mdf. Mdf is abrasive too.
A36 is cheap enough to play with. Cutters not so much.

 

[madmachinst]

Cutting air is pretty cheap. Then so is simulation in fusion.
The feeds for steel would smoke in mdf. Mdf is abrasive too.
A36 is cheap enough to play with. Cutters not so much.

I wish air could be measured( Not CFM or PSI). MDF abrasive? I thought that was glue and fine sawdust.

 

[madmachinst]

I see somewhere else on the internet they show how MDF can kill HSS cutters. Small stuff like 1/4" or less for aluminum jobs I do HSS cause my top speed only 7500 RPM so no sense in carbide. What kind of wood should I use that won't chip or crack? Remember, cheap and disposable is also a consideration. For example on Sunday I caught where I programmed a G41 for a 5/16 cutter when I actually had a 3/8" cutter in there. I hate doing that when I only have material for 1 pc. I would like to quickly cut a pc of wood slap it in the vice and catch any gremlins in the program. Could even run it all at 250% feedrate.

 

[Pete Deal]

Man that’s the dustiest stuff. I’d hate to run that on my cnc mill. Get some aluminum scrap and get to know the feed/ rapid over ride knobs.

 

[TeachMePlease]

I'd say you could cut Delrin... But unless you're getting drops from some other local shop, I think that's just as pricey as cutting Aluminum.

 

[DouglasJRizzo]

MSC and other houses have machinable wax which can be measured and Q/C'd as well as cut.
However, for me, I usually toss in a piece of aluminum scrap, and go the single block/rapid down/hand on the knob/look at the distance to go route.

 

[Archer120x]

The only time I have had coolant rot in 10 years is after the one time I cut wood.

 

[swatkins]

Check out the machinable wax. Easy to clean up. After use you collect it , remelt it
, cast it into a shape and reuse it.

 

[MikeBurgess]

Probably not the price point your looking for but tooling board would be great for testing its rigid and cuts fantastic, downside is it's not cheap.
Sounds like you're looking for a way to test a program so you don't break a $5 HSS mill on a $5 piece of stock that doesn't dull the mill or cost more than the stock and that's a hard ask.

 

[kenton]

HDPE is pretty cheap if you don't want to do wax.

If you are really cheap you can cut up milk jugs and re cast them.
I tried once over COVID, giant waste of time. Scrapped the pan as well.

 

[kb0thn]

When I was just getting started I used PVC bar stock or HDPE flat sheet to test things out. Plastics have come up a lot in price and aluminum is probably cheaper now. As your skills mature you start to get comfortable with pressing the button on more expensive stock and knowing you are likely to get a good part.

I do still use delrin round bar for proving out particularly complex lathe parts. Most lathe tools can survive a collision with plastic bar. When I got my first CNC lathe I spent about $600 getting 4ft bars of delrin in all of my common diameters. 7 years later there is still a bunch left and I know I've saved a few boring bars.

Maybe try to find a local shop that can give you some drops. I'm always sad at how many slugs and end of bars get wasted at my tiny shop. A box of donuts could probably secure you a fair amount of aluminum chunks to try tool paths on.

 

[Orange Vise]

CNCs are high consequence machines.

Mistakes in programming and setup will be made throughout your entire career. It's important to develop the ability to catch these mistakes on the fly, before they cause significant damage to your machine and tooling.

Most machines already have many tools at your disposal to help catch mistakes:

1. Feed hold
2. Rapid/feed override
3. Single block/Optional stop
4. Distance to go
5. Dry run
6. Raising the G52/common Z offset an inch or two above your part to cut air

You can also program your features to be very shallow in Z, say 0.0625". This can be beneficial when testing out adaptive and pocketing toolpaths.

Machinable wax can be used in conjunction with all these, but should not be used in lieu of them.

 

[William Lynn]

CNCs are high consequence machines.

Mistakes in programming and setup will be made throughout your entire career. It's important to develop the ability to catch these mistakes on the fly, before they cause significant damage to your machine and tooling.

Most machines already have many tools at your disposal to help catch mistakes:

1. Feed hold
2. Rapid/feed override
3. Single block/Optional stop
4. Distance to go
5. Dry run
6. Raising the G52/common Z offset an inch or two above your part to cut air

You can also program your features to be very shallow in Z, say 0.0625". This can be beneficial when testing out adaptive and pocketing toolpaths.

Machinable wax can be used in conjunction with all these, but should not be used in lieu of them.

This.
Forget the MDF idea, or try it and learn not to do it again. The dust is nasty and as mentioned abrasive.

 

[madmachinst]

Someone said poplar.

 

[jatt]

I even hesitate to cut like ridgy didge (real) wood in my dodgy ass Chiwanese bandsaw cause it runs coolant.

Easy n quick, but yeah it aint called the nasty, brown stuff for nuthin.......

Been getting blocks of some cheap plastic offcuts from a bearing supplier. Would give em a try before I put wood (espec that manufactured MDF shit) anywhere near a fancy arse machine.

 

[madmachinst]

I even hesitate to cut like ridgy didge (real) wood in my dodgy ass Chiwanese bandsaw cause it runs coolant.

Easy n quick, but yeah it aint called the nasty, brown stuff for nuthin.......

Been getting blocks of some cheap plastic offcuts from a bearing supplier. Would give em a try before I put wood (espec that manufactured MDF shit) anywhere near a fancy arse machine.

I can either put my M8 in () or hit the coolant off button as the pump activates. either will cut off my coolant no problem. Also not such a fancy machine

 

[M. Moore]

I have used mdf to test cut simple parts as I was learning my machine. I held my shop vac near the cutter to catch the dust. Carbide cutters will be fine, no coolant….
I usually moved the table down so I was making a very light cut. I made a lot of mistakes 4 years ago but I am getting much better now so I rarely use mdf anymore.
Quite natural for me after 30 years of furniture making.

 

[???]

MDF has formaldehyde in the glue. Wear appropriate mask etc.