Welded frame reference surface milling

Madis Reivik · Dec 20, 2019

Hello !

Imagine a welded frame and a need to mill reference surface (feet)

As the piece is not super-rigid, would it be better to use

Shell end mills, fine teeth, type H | ZPS-FN a.s.

Instead of usual 8-teeth carbide insert facemill.

I imagine that HSS piece has much lower cutting force.

Please share experience !

eKretz · Dec 20, 2019

Depends how shaky the setup is. Very floppy stuff you need to change your setup to suit. Use kickers or screw jacks and extra clamps if necessary. As far as cutting tools, if you still have a rigidity problem using carbide with sharp edges try a fly cutter with a razor sharp HSS tool and good clean-cutting geometry with fairly open clearance angles.

I would stay away from a fine pitch cutter. The more teeth in contact at once the more likely you will get chatter.

gbent · Dec 20, 2019

The more clearance under the cutter or insert the better. The standard 2 degree dish on the face mill isn't enough. And I agree with ekretz, you need to stiffen the feet with temporary bracing.

Limy Sami · Dec 20, 2019

+ another on brace brace brace and a flycutter.

Even sandbags ''draped'' over areas that aren't being machined can work wonders.

Milland · Dec 20, 2019

Limy Sami said:
+ another on brace brace brace and a flycutter.

Even sandbags ''draped'' over areas that aren't being machined can work wonders.

I agree with the advice given, with one other thought - smaller cutters, like a 12mm endmill will put less stress into the cut over a larger tool like a fly cutter. While stepping over costs time, it can reduce deflection and bracing requirements.

Madis Reivik · Dec 21, 2019

Hello !

I try to avoid dampening as far as possible.

Perhaps

Single angle milling cutters | ZPS-FN a.s.

is worth trying ?

Its a manual machine so stepping over is very bad thing

eKretz · Dec 21, 2019

Again, you want as FEW teeth in contact as possible if you're having chatter problems. And a fly cutter can be however small you'd like to set the tool...

Milland · Dec 21, 2019

If a manual machine, is it dovetail ways? And how old is it? How worn?

Before you commit to any cuts, test the machine by loading the frame as intended, then move the table around to the extends needed for the cuts, but with a precision level somewhere on the table or frame. Note each pad location's deviations from the nominal (table centered) readings.

If the machine is worn and you're moving to the extents of travel, you may find table sag complicates efforts to make all the pad heights and angles uniform.

Aside from that, sure, light cuts with that cutter you linked to should be ok.

Madis Reivik · Dec 21, 2019

Machine is quite large (FIL250) and in good condition, no sag problems. Low spindle revolutions (1800max) and ISO50 taper, so more teeth is better.
Box ways, if I remember correctly

Also, can You recommend cutting condition for that single-angle cutter ? What depth should I use on 80mm ?

eKretz · Dec 21, 2019

Have you even attempted a cut yet? We can theorize all day long, but until you have an actual problem to describe it's sort of a waste of time.

Milland · Dec 21, 2019

eKretz said:
Have you even attempted a cut yet? We can theorize all day long, but until you have an actual problem to describe it's sort of a waste of time.

Yes, this is reasonable. The OP's setup will likely determine cut parameters (does it sound good? It is good).

Madis Reivik · Dec 21, 2019

I have tried facemill, not so good. Therefore I had the HSS oldschool idea.

I have to spend 150..200 EUR so better ask first

Limy Sami · Dec 21, 2019

Madis Reivik said:
I have tried facemill, not so good. Therefore I had the HSS oldschool idea.

I have to spend 150..200 EUR so better ask first

IME you're still barking up the wrong tree, stick with a simple flycutter …(...which shouldn't cost 150 -200 EUR)

Madis Reivik · Dec 22, 2019

Yeah, flycutter.

Why not spend 10 times more time on machining

Milland · Dec 22, 2019

Madis Reivik said:
Yeah, flycutter.

Why not spend 10 times more time on machining

You should buy a giant wire EDM machine so you can cut all the feet at once with zero mechanical stress.

Limy Sami · Dec 22, 2019

Madis Reivik said:
Yeah, flycutter.

Why not spend 10 times more time on machining

Or twice / thrice that trying to get multipoint cutters to work.

Madis Reivik · Dec 22, 2019

Can someone share some cutting parameters for linked ZPS cutters ? With RPM its clear, but depth of cut ?
Share experience !

Limy Sami · Dec 22, 2019

Oh well

This is all I know of, but there may be more on line ….for these type of cutters ML112-Dovetail Cutters | Milling Tools Supplier | Cutwel Ltd

this is the cutting data https://www.cutwel.co.uk/FileDepository//ProductId - 195/Cutting Data ML112.pdf

Matt_Maguire · Dec 22, 2019

I think the shell mill (first post) is likely the better of the two if your goal is to surface the ends. The 20° helix angle with (what I think is top rake) of positive 8° is lower cutting force than the second form milling cutter. The latter is a 0° rake face on the bottom & side faces & tends to go bang-bang-bang. The correct arbor for the second one would also be more expensive. I usually climb cut on small millers with the first shell mill using 2/3 to 3/4 of the diameter in the work, they play pretty nice when you get the routine down. You do keep the feedrate up to near .1mm per tooth with cutting oil & they will last a long time

If I’m thinking right, this is like facing the legs on a folding table. If so → I’m likely going to make a connection to the table near the work end (horizontal spindle) or to a tall knee if it’s a vertical spindle. I’ve done plenty of wimpy weldments but they either have straps tacked on or bars C-clamped all over the place to stiffen it up.

Take pictures, we want to see this.

Good luck,
Matt

Bill D · Dec 22, 2019

As far as sandbags go. I have heard it is better to use something like gravel or scrap metal in a bag. Problem with sand is it can leak and get grit into precision surfaces on your tools.
Bil lD

Welded frame reference surface milling

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