Fixture plate ideas

My 1940 Alfred Herbert Mill is in the unfortunate position to only have 1 tee slot through the middle of the table - at the moment i am living with it and I get by.

Can anyone suggest ideas for a fixture plate (if that's what its called) to bolt to the table in order to give me more flexibility in holding things to the table.

My thoughts are for a 30-40mm thick steel plate approx 150mm deep by 300mm long with 3 tee slots machined into it and then this bolted down to my table with the existing tee slots.

Thoughts please.

You could use thinner aluminium jig plate with a series of tapped holes in it for studs, much lighter and simpler to make, and for hobby use adequate for most things, and no need to machine tee slots.

Chris Gunn

That will work, only problem I can see is you new fixture plate is likely to distort in the process. Best to stress relieve before milling & surface grind after the machining is done, you can find grinding facilities in most parts of the country. Or yes use ally plate as suggested above.

Tony

Edited By Tony Pratt 1 on 15/09/2021 12:45:17

There are a number of people who supply small tee slot plates (5" x 4" ). Two of these will give flexibility to your setups as you can use one or two and have them together or apart as suits. RDG and Chronos sell them for example. Since they are an attachment you can drill/tap them as suits and add holes for hardened dowels if required without doing something to the mill that can't be undone.

Martin C

Smiley removed

Edited By Martin Connelly on 15/09/2021 12:57:32

You could also just skim it on the mill, just make sure any gaps under it are shimmed so you don't distort it when doing the underside then flip it over and do the top.

Thanks for the suggestions - the table on the Mill even after almost 80 years is still very flat - I like the idea of the separate tee slotted plates - but I also want to make my own..... I'm mad like that.

Would that be a Herbert 0V? Mine had a single tee slot, I added a second slot midway between the existing slot and the front of the table.

I considered other options, a plate with three tee slots, would reduce vertical capacity too much, likewise a plate with an array of threaded holes. The latter idea would have been a pain to use, clearing the swarf out of the threaded holes!

John

For smaller work "grid of tapped holes" plates can be very useful. But tapping all the holes is a pain.

I've used 1/2" thick anodised alloy breadboards from Thor Labs for such duties and found them both satisfactory and not impossibly expensive given the time and effort of DIY. If you don't have suitable material to hand aluminium tooling plate or equivalent quality steel plates of suitable thickness approaches the cost of a Thor Labs breadboard. In my case possibly 1/4 more for the ready tapped product so worth the extra cost for me. Thor were quite happy to take my credit card details.

Thor Labs single density boards with 6 mm holes on 25 mm centres are here **LINK** https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=159

and double density ones in 5 spot pattern here

**LINK** https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1861

They also make round ones which can be useful on rotary tables. Especially small ones which tend to be short on clamp space.

There are other suppliers of similar items which may be better priced. Thor are simply the folk I know or, more correctly I suppose, knew.

Simple table clamps similar to those shown here **LINK** https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=191 work well with grid of holes plates. Easily made to suit the job. Way too expensive to buy!

Being so easy to replace they can be considered disposable. If one gets in the way I've been known to simply cut through it and swop another one in when the coast is clear. Helps that the grid of holes flexibility lets you use more, smaller, clamps than a T slot system. With less load per clamp loosing one temporarily is no great problem. Much easier than doing the clamp shuffle with the common, effective but somewhat cumbersome, sets.

More clamps sharing the load is nice when dealing with something easily distorted too. Real nice if its possible to line up a bolt or screw with a hole in the part too. More a repair than a making thing methinks.

6 mm or 1/4" screws / bolts can produce ample clamping for anything we tend to deal with. But they are less stiff than the larger bolts and studs used with T slots. Where stiffness is needed a suitably large stub with a short male thread on the bottom works fine. 1/2" deep tapped hole and 1" of all thread / studding works fine.

As ever whats best for you depends on what you do.

Clive

I had a similar problem with my small Atlas MF - which also only has a single central bed 'slot'

Fortunately, I had a steel plate (from a die casting machine) that had some existing holes that I tapped & added too. It's normally attached by two special bolts that fit the open ended slots (pre-existing) you can see but in the photo I needed to set the ER32 collet block back a bit for the horizontal milling and I used two of the fixture 'holes' for the table t-nuts instead.

Here I was milling flats on a part held in the ER collet. I did originally purchase a slotted table for this purpose but it's been used elsewhere as this (longer) lump seems to do the work just fine. Mine is about 25mm thick but it could be half that without any issues I think. I haven't bothered to thin mine down as yet.

It's also very useful to make a clamping bar to match the plate holes!

Regards,

IanT

PS The slitting saw in the second photo was being put on for another job when I took the photo to show the clamp bar etc from the previous work. This is a useful workshop diary/reminder - as my memory sometimes fails me. I sometimes find bits that I know I've made but cannot for the life of me remember why!

Digital photos really help me jog my memory these days!

Hi John

Mines the Herbert 10s - and research seems to suggest it might be the only one still working...... I have made contact with another Herbert user but he has the 10 - It seems the 10s is slightly different.

I had considered cutting another slot but I was steered away from the idea by others - I did wonder why it wasn't recommended as the table is almost 1" thick - now I can see in the last picture the harrow table with 3 slots I can't see any reason why not to mill another slot in my table.

Not sure which photo you are referring to - but if it's the Atlas, there is only one T-slot but it has two 'V' grooves either side of it that are accurately machined (in effect built-in V blocks). Round material can be quickly clamped on these Vs for some machining operations. Might be another option for your table and possibly easier to cut too.

Regards,

IanT