Member postings for JasonB

I'll take a look

You are never going to do it quickly on a small mini mill due to the size of cut it can comfortably take. Using a large cutter that puts a lot of load on the slow running motor won't be quick in the long run when you have to spend time repairing the machine but I can see Ketan and the boys rubbing their hands now at the prospect of more sales of spare parts

If you can't size the hole then you have problems somewhere either rushing with big cuts that deflect things or tool geometry is rubbing somewhere. Boring head is more accurate and will give a better finish than any holesaw, rorabroach, blacksmiths drill, etc

You should be able to use the quill lever to feed the boring head fairly quickly, for best results use the fine feed for the finish pass

Edited By JasonB on 28/09/2023 09:55:25

Don't quite know if its a solid block or sheet, but this is F360 cutting it from 5mm sheet. Few tabs to hold it in place and a ramping contour that is constantly lowering the cutter into the work as it goes around. Also included the Post Processor to show how quickly it generates the code.

Thanks dealt with

What FB Group Tony? Sounds like there may be some good tool crash pictures coming

I thought that may be why he needed the angle so he can tell the cutter to move through 60deg of a 0.25" radius if using a 1/2" cutter

Jason is fine

To me its not the best way to go about it using a 1" dia cutter into a 1/2" radius internal fillet will give a large engagement angle that is bound to chatter or deflect if the machine is a bit worn.

Better to use say a 1/2" or 10mm cutter to cut the profile leaveing say 0.2mm and then do a full depth finishing pass. would also allow the notch at the end to be partly machined.

That's a nice round number for the angles, 30deg so your angle between the two black lines is the complementry 60deg

Edited By JasonB on 27/09/2023 22:37:45

Got the rest drawn up just waiting for that info then I'll let you know but will be turning off soon so you may need to wait until morning

Would want to know the radius of the internal fillet and the width of the straight part.

Get some CAM on you machine at the same time and let the 'puter work out the path rather than write code

I decided to start with the two spacers that go between the side plates to get a feel for what the grade of Gunmetal was on some parts that were going to mostly be out of sight. I started by just taking skim cuts off to remove the quite steep draft angles thus giving me some flat surfaces to hold while the 4 long edges were brought down to final size taking similar amounts off opposite faces so that the inverted "T" section stayed central. For almost all the "flat" milling on this engine even the quite small parts I used a 6 insert facemill with APKT inserts which are made for use on non ferrious metals. Most other milling was done with cutters intended for use on Aluminium but they also work well on other non ferrious metal, here you can see a two flute cutter has been used to square up the ends.



After a quick tickle of the remaining cast surfaces with a carbide burr in the Dremel the various holes were drilled and tapped M2.5 with a spiral flute tap



I was not that happy with the varying thicknesses of the end plated even after averaging out their thicknesses so decided to clean things up a bit more with a 4mm milling cutter which evened things up.



Using the face mill again I skimmed the top and bottom flanges of the side plates so that they could better be held in the mill vice to take off just enough material to clean up the flange edge. In most cases the castings were quite generous with machining allowances with the average being around 2.5mm (3/32" )



The casting was then flipped over to do the flat inner face and then a bit more off the top and bottom edges to bring the castings to the final height



The 2 flute 10mm cutter was put into use again to finish the ends with full depth passes of the 1/2" thickness, again taking a bit off each to leave as similar a flange thickness as possible each end.



Clearance holes were drilled and then spotfaced for the fixings into the spacers



The parts where then screwed together with temporary cap head screws, the assembly centred up in the mill vice and the holes for the trunion and crankshaft bearing blocks drilled and taped. The drawings also call for a couple of notches to be milled out to give clearance for the plates where the trunions bolt to the cylinder otherwise they would collide as the cylinder oscillates.

have a look at some of the man made slate, the Redland interlocking ones look good and are easy to fix. Another option is the lengths of metal roof tiles such as these again easy to fit and won't crack but still look the part, I have them on my conservatory and they make it useable all year round unlike the old twin wall polycarb (there is kingspan under them

So I'm told

ME used to be at Wembly and Ally Pally long before that. (Sandown & Ascot not Epsom more recently)

People wanting the bargain basement goods direct from the far east does not help the traders either so if you don't support them you loose them and shows.

Edited By JasonB on 27/09/2023 15:24:37

Thanks ADY1 so thats a third engine as I had seen mention of "Hoppy" a hit and miss engine kit they dis that sounds like it may have needed some crankshaft balancing. Though Henry would be the only ready machined of the three.

Most traders were finding it hard to cover their costs so harder to fill a more expensive venue than one the organisers already own. Would be even higher costs for exhibitors/traders now what with fuel prices and ULEZ

A couple of not too good photos for Michael

The jaws are 8.8mm square and the clearance hole for the 10-32UNC thread is 5.1mm. A file test suggests the metal is harder than just untreated mild steel so may have had some form of heat treatment or just be a higher carbon steel.

The dark area suggest one side partly fractured prevoiusly and the brighter where it finally gave up

Another clamp is showing a crack down one side

Given that the mini-mill does not have a great deal of power and may struggle to drive the larger blacksmiths drills even if working up in a range of sizes or the thicker kerf of a rotabroach. I would suggest stitch drilling out most of the waste with a 7mm drill bit which will allow the motor to run at a comfortable speed and not overload it or the plastic gears. Then take it out to final size with your boring bar(head? )

This is a fairly easy layout, I would drill the holes 6mm and then open out to 7mm to reduce the risk of the holes wandering as they break into the adjacent hole. Holes at 90deg are spaced 8.5mm from ctr, the ones on the 45angles are 6mm x 6mm from ctr which keeps it simple if using hand dials

Won't really work ADY as the slots need to be radial otherwise what runs in them will just jam.

When you say main dealers are you talking of Model Engineering suppliers? if so they are likely to be more expensive than a commercial steel stockholder. Metric 25 x 10 would likely be cheaper than imperial these days too. Expect to have to buy 6m lengths