Cutting this intricate shape

[Chris HammondParticipant @chrishammond37041]

Guys, some advice for a newbie please.

How would you go about tackling the cutting of this shape out of 8mm mild steel? I have a manual milling machine, no fancy CNC unforch.

What would be your recommendations? (I can't afford water jet cutting for the project).

Thanks.

Have never been able to master the picture upload on here, so here is the link….

http://s1079.photobucket.com/user/chrishammond1/media/Project2_zpsrf6a72hg.jpg.html?filters%5Buser%5D=146094701&filters%5Brecent%5D=1&sort=1&o=0

 

Edited By Chris Hammond on 18/01/2017 16:00:05

[Chris HammondParticipant @chrishammond37041]

[Chris HammondParticipant @chrishammond37041]

Nah, can't get the picture to show!

Edited By Chris Hammond on 18/01/2017 15:59:46

[John HaineParticipant @johnhaine32865]

8mm – are you sure?

Chain drill round to rough out, then lots of work with files/angle grinder/mill (if it will fit). By the time you'd finished you'll be thinking that getting it laser or water cut would have been worth it!

[MikeParticipant @mike89748]

Be patient – it just takes ages to load…………

[JasonBModerator @jasonb]

Do all the drilled holes first while you have some straight edges to work from . Then I would work out the position of the holes that will form the various corners of the cut outs and drill them next. You can then remove the metal with a mixture of sawing and stitch drilling.

If you have not made a set of frames before then usual practice is to start with hot rolled steel not bright as it will be less likely to go bananna shaped. Mark out a couple of holes at either end on one piece then clamp them together and drill as a pair. unclamp, deburr and then bolt or rivit together, this will ensure that the rest of the holes and cuts all match across the pair of frames

8mm does seem thick for a frame that is only 313mm long

 

Edited By JasonB on 18/01/2017 16:13:20

[John HaineParticipant @johnhaine32865]

…and if you bolt 2 of them together you're cutting through 16mm…

[Brian OldfordParticipant @brianoldford70365]

Posted by JasonB on 18/01/2017 16:09:54:

. . . . . . .8mm does seem thick for a frame that is only 313mm long

It looks representative of bar frames. (Very popular in N America).

[Chris HammondParticipant @chrishammond37041]

Hmmm, thanks gents. Looks like I better get some arm strengthening exercises going!

I have specified 8mm because, when then plan was enlarged, it measures 8mm on the drawing. Is that not best practice?

It is an American locomotive frame yes. Would you recommend down sizing the thickness some what then?

I briefly considered aluminium but I believe it would be too weak and subject to cracking.

Thanks for the tip Jason re the hot rolled steel.

Appreciate your help as always guys.

[KWILParticipant @kwil]

By the time you have laid out and drilled all those stitch drilled holes, then cut it out. I would have milled it out using coordinates. There are quite a number of nice corners you could drill (and bore for larger radii), both plates at the same time to ensure they are and remain the same, That top line looks very weak along the top right edge.

[Chris HammondParticipant @chrishammond37041]

Kwil – yes to mill it out with a CNC would be ideal. Unfortunately, I don't have that facility.

I am open to anyone wanting to take the cutting work on

[Brian OldfordParticipant @brianoldford70365]

Posted by Chris Hammond on 18/01/2017 17:00:52:

. . . . .

I have specified 8mm because, when then plan was enlarged, it measures 8mm on the drawing. Is that not best practice?

. . . . .

I suggest you leave as is. Although similarly sized British plate frame prototype with plate frames would be thinner they would also be significantly deeper too.

[KWILParticipant @kwil]

Chris,

I do not have CNC either,

Have you asked a supplier about costs of Waterjet or Laser?

[Chris HammondParticipant @chrishammond37041]

Ok – thanks Brian.

Kwil – i have had a price off one waterjet cutter £120 + vat – so £144 plus delivery circa £15. Way too steep for my budget.

[Chris HammondParticipant @chrishammond37041]

Brian – please could you explain how you would mill it out using co-ordinates?

Would that be by using some kind of template?

Thanks

[JasonBModerator @jasonb]

Here are a couple of examples of stitch drilling followed by milling which is a method I quite often use on plate upto 25mm thick.

Drill a series of holes who's edge is just inside your cut line, looks like you work in metric so use a 6mm split point drill as that won't require spot drilling first and just wind the mill table along 6mm drill a hole, wind drill, etc. If you get it right the waste will just drop out if not there is very little to saw. Follow by a couple if rough cuts to remove the drilled edges followed by a final full depth pas sto clean up.

In this shot you can also see a boring head being used to get a large internal radius on two bits of 5mm plate clamped together

Same parts after the drilled edges have been milled

Another job this time one 5mm plate, all fixing holes drilled first and larger holes done with boring bar

Hole stitch drilled out and being milled

Doing a curve on the rotary table

Job done

Stitch drilling 25mm black bar

[Chris HammondParticipant @chrishammond37041]

That is beautiful work Jason. Thanks for taking the time to show me – it has really helped.

Looks like a decent sized mill you have – may I ask what it is? Mine is a Chester Cobra – so I guess i would be better taking smaller cuts to achieve the same result?

[duncan webster 1Participant @duncanwebster1]

You used to be able to get Abrafiles, a sort of cylindrical saw blade. Taken carefully they will cut 8mm (well I cut 2 off 3mm at the same time on one of my locos. They will start from a much smaller hole than a normal saw blade, and if you are careful you can cut round corners.

If you've got a plasma profiler near you I'd take the drawing and discuss it with him. It's not as accurate as laser or water jet, but just leave a bigger finishing allowance. It's a lot cheaper.

Having said that laser is cheaper than water jet (more expensive than plasma), and with the right machine you can do 8mm.

With all the hot cutting techniques you need to whizz over with a grinder any surface yoiu intend to finish machine.

[John Stevenson 1Participant @johnstevenson1]

OK sounds like a bit expensive but basically laser cutting and water jet are costed out the same way. They need to draw it first as costs are worked out on material plus distance traveled and running costs are built into the two of them.

So I took the drawing as a jpg, cleaned it up a bit.

Then saved this as a dxf file which the laser software can read. I have sent this off to my suppliers to get an idea of what it should cost. I'll have that back later tomorrow so if I get time I'll repost with prices.

I have took a bit of leeway on the radius's and curves from the jpg but it will be very close.

[Nick WheelerParticipant @nickwheeler]

In 8mm steel a good quality blade in a sturdy jigsaw will quickly do most of that. Then you could bolt both pieces together and finish them with files etc.

[Neil WyattModerator @neilwyatt]

Posted by Chris Hammond on 18/01/2017 15:59:24:

Nah, can't get the picture to show!

Edited By Chris Hammond on 18/01/2017 15:59:46

Chris, look at the first post on the first thread in the first topic of the first section of the forum

How to post photos (including photobucket):

[Chris HammondParticipant @chrishammond37041]

Thank you Neil… I knew there would be a logical way but totally missed that sticky! Doh.

[Chris HammondParticipant @chrishammond37041]

Thanks all for your time and suggestions.

John, I have the frame drawing in Illustrator as a vector file. It can be saved as a .dxf directly from Illustrator, so no loss in quality at all. It should also mean they don't have to draw it again, therefore saving cost?

Interesting to know what kind of price you get.

[Chris Evans 6Participant @chrisevans6]

Jason's method is how I make engine plates for motorcycles, does not take to long at all. With the job marked out with decent scribe lines it is easy to "walk the milling cutter" around the shape. If you master posting photo's show us some progress when you get there. We love photo's so easy to see what people are doing. Chris.

[John HaineParticipant @johnhaine32865]

Regarding the thickness, 8mm still seems excessive to me. What gauge are you building for, and what frame thickness would people usually use for that gauge? You said that is what you got from scaling up the drawing, but in the drawing the thickness may not be to scale – if it was it could easily look like a line.

[Author]

Posts