CNC Feasablity for small project?

[Martin King 2Participant @martinking2]

Hi All,

I am looking at trying to generate a small run of this small item in steel or brass.

Initially about 20 off maybe 50 later on.

Here is a F360 of the item which is approx 35mm by 21mm and 14mm tall.

I wonder what the feasability of this is in terms of cost and ease of fabrication.

Can anyone help me with this please?

Regards, Martin

[Martin King 2Participant @martinking2]

[Martin ConnellyParticipant @martinconnelly55370]

Has it got any hidden features underneath it. If not could it have a couple of threaded holes to hold it on a fixture, it would make it reasonably easy to setup and machine a multiple of them.

Martin C

[Martin King 2Participant @martinking2]

Hi Martin C,

The original is cast iron with hollowed out sections on the underside but I have simplified the design somewhat to make it easier to fabricate. The hole in it will be tapped for 9/32W.

There is also a similar part which has straight not curved sides which I would also need the same numbers of..

Cheers, Martin

[JasonBModerator @jasonb]

Or you could cut from 20mm tall material and hold in a vice, just skim off the waste as a second op, the two flat ends would make it easy enough to hold for that.

Is that hole threaded? also what sort of finish in the sloping side of the slot as that will need more passes the finer you want the surface finish to be.

Edited By JasonB on 18/04/2020 19:08:42

[DC31kParticipant @dc31k]

Can you size the radius of the groove and the angle of the slope to suit a common horizontal mill cutter?

Run your 20mm stock through the horizontal (two passes) and then transfer to CNC.

[Jeff DaymanParticipant @jeffdayman43397]

Is this item for hobby / personal use?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Jeff Dayman on 18/04/2020 20:42:05:

Is this item for hobby / personal use?

.

Does it matter ?

MichaelG.

[Martin King 2Participant @martinking2]

Hi,

These are fences for a stringing hand router that are always absent. I have at least 15 of these tools needing fences. Each one comes with a straight and a curved fence for different work.

This is hopefully a commercial project so not looking for any favours just a way of making them in smaller quantities than a larger company would not be interested in.

I am not at all au fait with CNC but would like to dip into getting items made if possible and economically viable.

There are several other projects for making rare and hard to find parts for tools that I have patterns.

Jason, The hole is threaded 9/32" Whitworth and the slot does not need a fine finish, it is as cast in the original.

DC31k, The slot could probably be done with a a 1/4" ball end cutter and have parallel sides.

The drawing shown is as close to the original as I could get for an example only.

Cheers, Martin

It is purely for clearance of the string cutter at minimum settings from an edge.

[Martin King 2Participant @martinking2]

Here is more of a top view showing the curved sides:

Martin

[Anonymous]

Posted by Michael Gilligan on 18/04/2020 21:50:48:

Does it matter ?

Yes it does. Now we know the part is commercial we can ask the single most important question. What is the target price to put the part into stock?

Andrew

[JasonBModerator @jasonb]

Yes I would say it matters as I would not like to think of someone doing the work as a favour to a regular fellow member for a bit of pocket money and then for that member to be able to sell the planes on e-bay at a far greater price due to having the missing part.

Martin, there is an option with F360 to share the part which would allow any interested party to study the file more closely, if you go to "file" top left it's in the dropdown and you can post the link it produces here.

I doubt I would be cost effective as I have not set up any coolant /air to clear swarf so you would have to pay me to stand infront of the machine plus I don't have quick tool change which would add to costs.

If I were doing a batch for myself then I think I would stay with my suggestion of cutting from 3/4 or 20mm tall stock and run 3 or 4 parts on one length of bar which would reduce tool and work changing by quite a lot. Think about whether the slope of the slot could be done at another setting with the part at an angle so side of a ball nose cutter could be used as it would need less passes so may be faster than working down the slope in small increments. positional accuracy of the hole would nee dto be known as it would be quicker to go straight in with a split point drill and risk a tiny chance of wander Vs using a spotting drill first which would mean another tool change, also is the hole drilled through and how much of it needs to be threaded.

You may also want to try the couple of CNC services that have an ad in ME such as 17D-ltd who will do small batch work.

Edited By JasonB on 19/04/2020 07:34:52

[Speedy Builder5Participant @speedybuilder5]

Investment castings ? What sort of tolerances would you be looking at?

[pgk pgkParticipant @pgkpgk17461]

I'll ask the questions since I'd like to know the answers:

Apart from authenticity does the part have to be pure metal: hardwood, HDPE, 3D printed plastic or metal, how about a master mould and then that clay stuff that can be fired to look/feel like metal?

How would costs compare to making the things from solid when runs are 20-50 pieces?

Apart from the threaded hole of course a moud could be assembled from several sub-units that'd be easy to make.

pgk

[Martin King 2Participant @martinking2]

Hi Jason,

Your point is of course totally valid. I sell tools and collectables on EBay as I think is fairly well known on here.

There are many tools that only sell well if complete with all parts so that they are at least useable.

For the "collector" market the tools must be complete with totally original parts to do well, but "good user" tools have a following and it is this market that I am looking to address.

In the past I have made partial sets of cutters for certain planes but it has been an uphill struggle for me and very labour intensive as they were from gauge plate and to quite a tight tolerance, also needing heat treating etc. There was no way that I could find of doing them in small quantities commercially so I did them myself but not really worth the effort. It did however allow me to clear a lot of otherwise non saleable items (as was), but valuable items that I had accumulated with other stock.

With these particular fences I have already 3D printed some prototypes of the STRAIGHT SIDED fence which came out OK but the threaded area that takes a locking thumbscrew is far too weak to be of use. I tried reinforcing the underside with a brass threaded insert but still no good.

Thus I need these in steel or brass, I am pretty sure that casting is WAY too expensive.

As to an economic price per part, this is pretty unknown territory as I have no knowledge of the production costs for something like this. It is entirely possible that cost is why this has not been done before!

I may not be doing myself any favours here but here are some pics of the actual original item as my F360 drawing is very much a first attempt. The underside and end cut outs are not needed.

In use this is bolted to a long slot in the tool and used to keep the cutter a known distance from the edge of the work being stringed, this fence is for curved edges and one uses the other item for straight edges.

Thanks to all for the interest in this.

Regards, Martin

[geoff adamsParticipant @geoffadams14047]

Martin sent you a PM

Geoff

[Chris Evans 6Participant @chrisevans6]

In my working days I would have wire edm cut those, not cheap though.

[Martin King 2Participant @martinking2]

Hi All,

Out of interest here is another often missing part that I have managed to 3D print and have now sold with its plane to several customers with good comments from the buyers. This one has no threads so is not stressed in use:

[JasonBModerator @jasonb]

Certainly a market for the hobby woodworker who wants a functioning tool and is not too worried about originallity.

Cutting from cast iron rectangular bar would be another option to think about, bit more expensive than steel though less than brass and it would cut more easily than steel on smaller machines so you would get the cost of material back in time savings and at least have the original material. Though if the likes of Lie Neilson are anything to go by the bling of brass would be more popular!

For pure ergonomics of use the part may benefit from having a chamfer run around it, at least on the underside again puts up the run time bit sould save on manual or mechanical burr removal.

[CirclipParticipant @circlip]

Don't reject casting offhand, only top and bottom surfaces need machining.

Regards Ian.

[Martin King 2Participant @martinking2]

Hi Jason,

As you can see the original has slightly rounded edges (fillets?) on the casting.

[Anonymous]

Posted by Martin King 2 on 19/04/2020 08:36:30:

As to an economic price per part, this is pretty unknown territory as I have no knowledge of the production costs for something like this.

That wasn't the question I was asking. We need to work the other way round. To start with, what do you think you can sell the part for? Then take off net profit, packing and delivery costs and any other costs not directly associated with manufacture, like advertising for instance. The figure left is what you need the part to be made for. Once you have that figure only then do discussions about materials and manufacturing techniques make sense. You also need to make some decisions about form versus function. Clearly the original was cast. Making a part that will have same functionality will be a lot cheaper than making a part that has the same functionality but also has all the draft angles included so that it mimics a casting. It might be an idea to check the thread; 9/32" Whitworth isn't listed in my old copies of Machinery's Handbook, but available taps seem to be both 18 and 20 tpi.

Andrew

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[duncan webster 1Participant @duncanwebster1]

If you want 50 off I'd get them cast. There is a small foundry in Wigan that would do these, no doubt others. You could 3D print the pattern, if you have several patterns so they can mould/cast more than one at once it comes out cheaper

[William SParticipant @williams]

Evening all

My dad has the plaster moulds for the lost wax casting process for all the standard accessories for the tool in discussion, The straight fence, the curved fence and the little locking screw.

These were used to complete his No.66 and his work colleagues tools too, (each person having what the other required!!)

Moulds were taken from each original part and used to produce wax copies which were subsequently cast. The castings were done by my grandad who had a non ferrous lost wax foundry (this has subsequently been wound up owing to ill health) If interested I might be able to produce and supply required waxes, if you or someone can find a foundary to be able to invest and cast the components.

Being a non ferrous foundry the ones my dad have are cast in bronze. Pictures of finished articles can be supplied if interested, (required tool is in a furlonged state!!)

One thing to note is with any casting process there is shrinkage and because these are moulded from originals, they will end up slightly smaller. However the part was increased before moulding on the critical area (the key that prevents rotation) to machine to size.

Hope this is any help.

Many thanks William.

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