B.Hick & Son oscillating engine

I used 8BA on mine because the 7BA Nuts looked too large and ugly. Apart from the fact that you are going to struggle to get a spanner in to tighten them. On this part I used a clearance hole in the base of both and put a slotted bolt up from under the baseplate, into a nut held in a pair of tweezers and then tighten using a screwdriver from beneath 

A point to note: The whole model uses only 10BA and 8BAs (or you are going to struggle with over hanging nuts and no one wants to see their nuts hanging in mid air  )

Jo

I have mostly use undersize nuts

Strangely when I used to use BA I very seldom used 8BA, the Fowler had a few but can't think of many stationary engines that I used it on. Occasionally used as an equivelent to #2 UNC on the hit & miss engines

Now I use metric fixings M2.5 is very close to 7BA and I then go down to M2 which would be 9BA. I have taps & dies for M2.2 (8BA) but don't think they have ever been used in almost 40yrs.

Quote from: JoI used 8BA on mine because the 7BA Nuts looked too large and ugly. Apart from the fact that you are going to struggle to get a spanner in to tighten them. On this part I used a clearance hole in the base of both and put a slotted bolt up from under the baseplate, into a nut held in a pair of tweezers and then tighten using a screwdriver from beneath 

A point to note: The whole model uses only 10BA and 8BAs (or you are going to struggle with over hanging nuts and no one wants to see their nuts hanging in mid air  )

Jo

I'm just starting to gauge the size of the model having worked on the base; it's a 'little'un'. Hmmmm, no definitely no over hanging nuts 

Quote from: JasonbI have mostly use undersize nuts

Having under sized nuts on a stud  The other offence is having a stud that has more than 1 1/2 threads showing above the nut 

Jo

Quote from: Jo

Having under sized nuts on a stud 

Better than having nuts that look too big.

Lets take that 8BA as an example which the standard BA hex measures 0.151"

At 1/12 which this engine is supposed to be that 8BA thread would come closest to 1" in old money.

Although probably before standards if we take the hex size of pre war 1" whitworth nuts as 1.662 - 1.670" then that ba hex is going to be too big as 12 x 0.151" = 1.812".

So I'm happy to come down a size on ALL the hexs be that nuts on studs or bolt heads as they come out closer to an old Whit hex.

My M2.5 nuts and bolt heads are 3.5mm AF which at 12 times larger is 42mm AF and the 1" Whitworth AF in would be 42.16mm. Or on the model a difference 13 microns which is good enough for me

As for all threads being 8 or 10BA, this drawing would seem to say different

I'll leave Jason to help you Sanjay, he clearly knows more about making one of these model engines than I do.

Jo

I'm the LEAST expert in these matters, but will go with whatever will work and look right! 

In the meantime I've been cleaning the standards and I they look nicer ......... I think, hope!

Dare I say the flutes look a bit wonky May just be the screen is a lot largerthan the part.

Looks like you may have plunged in half way up and then moved either way to form the slot. A 3 or more likely 4 flute cutter was used and for some reason has pulled a lot sideways, to the left a syou cave cut in one direction an dto th eright when cutting the other way.

You are very much allowed to say that and interestingly the end mill snapped and I used another one on the 2nd standard - this worked out better for some reason even though that was a 4 flute cutter, see far RHS - oh well, I guess I need to invest in a 2 flute 1/16" end mill or slot drill?

I may just make an insert as Jo did and see if that works out better, I still need a slot drill though 

The right half of the one on the right are fine.

It could be that the cutter was getting blunt, that can also cause them to be pulled sideways. This image shows the difference in cut from a blunt 3-flute cutter on the left to a sharpened one on the right , particularly visible a sthe cutter exeted the cut in the foreground. Burrs are also a give away that the cutter is loosing it's edge.

Try these and also look at their shop for 4-flute cutters for ferrous.

https://www.aliexpress.com/item/1005005873344840.html?gps-id=pcStoreJustForYou&scm=1007.23125.137358.0&scm_id=1007.23125.137358.0&scm-url=1007.23125.137358.0&pvid=5bfd8ef2-5066-4774-84e6-feda13bc40b6&_t=gps-id%3ApcStoreJustForYou%2Cscm-url%3A1007.23125.137358.0%2Cpvid%3A5bfd8ef2-5066-4774-84e6-feda13bc40b6%2Ctpp_buckets%3A668%232846%238110%231995&pdp_ext_f=%7B%22order%22%3A%22406%22%2C%22eval%22%3A%221%22%2C%22sceneId%22%3A%2213125%22%2C%22fromPage%22%3A%22recommend%22%7D&pdp_npi=6%40dis%21GBP%215.37%212.69%21%21%2147.52%2123.76%21%40210393bd17792841055367812e10bb%2112000034656882494%21rec%21UK%21855056161%21X%211%210%21n_tag%3A-29919%3Bd%3A66763ea8%3Bm03_new_user%3A-29895&spm=a2g0o.store_pc_home.smartJustForYou_2010531288031.1005005873344840

And even with a sharp cutter (which makes a huge difference as the others mentioned) its always best to make the first cut back from the finished position then make a final light cut to finish it. If the slot is the same width as the cutter, thats not feasible, unless you can go one size down on the cutter. Narrow cutters will usually pull/flex a little bit into the work.

If you do go with an inset strip then you have a few more options as the cutter can run in from the edge.

I quite like the central one which is what you quite often see on Triglyph with the recess starting right at the bottom but stopping short of the top. You could cut with a plain endmill as the left options a ball nose as the right or even a Vee cutter as that was quite common though they tended to have straight not rounded tops.

"Triglyph" a group of three similar slots found on a frieze above columns.

So many options/possibilities - I need to see what I have in terms of tooling, also need to make a suitable size strip. I think its worth doing 

Third attempt/time lucky?

I found a reasonably small ball nose end mill and a bit of scrap brass, hopefully it'll pass muster