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Chester model b fitting new vise

Cross slide slot alignment insert

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James Margrave11/01/2021 01:28:20
5 forum posts

Hi guys I've got a chester model b. It's quite a few years old but got given it and it's has hardly been used.

I've decided as I'm going to keep it as fir the small work I do do it's actually quite useful and despite having its limits it just about does what I want now it's had everything adjusted and quite a bit changed so there is no play and is far better aligned. I mostly make odd bits for marine engines bolts, new inserts, machining bits out to fit bearings ect.

I've just spent a small fortune on some new equipment for it as its good quality stuff and if I do get a better lathe it would only compliment a better lathe, the stuff also makes the chester b far better than the stuff you get stock so it's not money waisted as alot of the stuff my brother inlaw said to get (works as a precision engineer) and its also stuff he uses on his own lathes and mills.

One of the items is a new vise the stock one is far too small and not very accurate or good but is fine as a tool post holder and that's about it but I will still need to use the original vise as atoll post holder. The new vise will be used for any drilling and milling. The new vise comes with 2 t-bolts and nuts. But it has an alignment slot grove down the middle with the 2 holes in and has 2 cut outs at the end for the t-bolts to hold the vise down.

My problem is the new vise didn't come with the small rectangular blocks that bolt onto the bottom of the vise in the slot so it sits square in the cross slide grove. You'll have to excuse me but I can use the machine but don't know all the parts / terms. What are these blocks / keys, alignment studs called as I've looked but can only find t nuts or a t slot inset (for myford lathe). The stock vise you can just undo the t bolts and lift the vise off and then refit as these 2 small block fit into the cross slide and align it perfectly and you just redo up the t bolts to secure from moving.

Do I just but t nuts and remove the wider shoulders or is there a specific name for these little alignment blocks? I'm also assuming they come in different sizes? Or do you have to mill them down to it fits your particular lathe?

clogs11/01/2021 07:28:49
587 forum posts
12 photos

I dont know much but all the vices I have none of those blocks....(6-8).....even mag bases .....

if u need accuracy I use a dial gauge and prat about a bit....there other ways if u dont have a dial gauge.....

it doesnt take long even on the heavy vices to get them square.....

also it's handy if u do need a little of square cut....

not done it yet11/01/2021 08:05:20
5382 forum posts
20 photos

alot of the stuff my brother inlaw said to get (works as a precision engineer) and its also stuff he uses on his own lathes and mills.

I would suggest that BiL might be the best person to sort you out with something?

Martin Connelly11/01/2021 08:48:58
1610 forum posts
176 photos

The little blocks are tenons. I would suggest making a round one on the lathe and only fitting one. This will allow rough mounting of the vice then with one side supported/located you can rotate the vice around the round tenon and use an indicator to set it parallel to the ways. The round one does not need to be a tight fit, it is only there to act as a point of rotation. This method also allows the vice to be set at an angle if required.

You can make two tenons if required, they do not have to be hard as they can be rotated to a new position if they wear. It may be best to make them looser to allow final positioning with a DTI when required.

Martin C

Edited By Martin Connelly on 11/01/2021 08:54:41

Nicholas Farr11/01/2021 08:58:40
2550 forum posts
1211 photos

Hi James, I take it this is the machine you have.

model b lathe.jpg

The blocks you refer to are just keys and are not a necessity and as Clog says, use a dial gauge to set your vice square, nip it down lightly and tap it square with the dial gauge on the fixed jaw of the vice and then fully tighten it down.

Regards Nick.

P.S. use a mallet/hammer to tap the vice square, not the dial gauge. angel

Edited By Nicholas Farr on 11/01/2021 09:01:40

Paul Lousick11/01/2021 09:06:57
1648 forum posts
613 photos

Hi James,

The rectangular blocks are called "keys". Although most machine vices come with key slots, very few will come with keys. The main problem is there is no standard for the width of keyeways on milling machines or vices. Unlike a key on a shaft that is specified for a particular shaft diameter.

Keysteel is available to suit the width of standard keys and just has to be cut to length and a hole for the retaining screw machined.

If the keyway on your vice is a different width to the keyway width on your mill table, you will have to make a special stepped key, with the top width different to the bottom. As you already have a mill, it should be no problem.

Although the keys are not necessary and if the slots are accurately aligned with mill table, they make the installation of the vice very quick for most of the milling operations. Its only when you want the best accuracy that you use a dial indicator for setup.


Edited By Paul Lousick on 11/01/2021 09:13:57

Martin Connelly11/01/2021 09:08:47
1610 forum posts
176 photos

Ha, loose language costs gauges to coin a phrase blush

Martin C


Edited By Martin Connelly on 11/01/2021 09:10:35

Paul Lousick11/01/2021 09:16:08
1648 forum posts
613 photos

Martin, Terminology depends on which country and which industry you are in..



Edited By Paul Lousick on 11/01/2021 09:19:18

JasonB11/01/2021 09:31:38
19568 forum posts
2142 photos
1 articles

Half way down this page I showed how to alter the keys if the slot in the vice is wider than the mill/lathe. You could do the same with home made keys which are just a block to fit the vice with a counterbored hole.

Howard Lewis11/01/2021 12:05:20
4143 forum posts
3 photos

If the vice has slots in the bottom face, you can either make keys or dowels (probably stepped )

The principle is that the key locates the vice to the table, accurately, so that alignment is correct whenever the vice is fitted to the machine. hence the keys or dowels need to be a snug fit in both vice and T slot.

There may well be tapped holes in the bottom of the slots in the vice. These are for the capscrews or countersunk screws to retain the keys / dowels within the slot, so that they do not fall out and get lost when the vice is removed from the machine.

So you need to measure the width of the T slot, and the slot in the vice accurately.

They are unlikely to be the same size, so the keys or dowels will be stepped..

To make stepped keys, I would suggest milling the raw material to the same size as the wider of the two dimensions. (Rather than make two separate keys, start by making one which is long enough to be cut to produce two keys as a final operation before deburring.

Having the material a snug fit in the larger slot, the upper part can now be milled to the dimension of the narrower slot. The dimensions need to be such that the key in the vice is the same depth as the slot in the vice, and that the part of the key that fits into the T slot is slightly shallower than the T slot.

The double length key can now be drilled (and counterbored ) for the retaining screws which will screw into the tappings in the slot in the vice.

Before final deburring, the material can now be cut to length to produce two keys, to be fixed into the slots in the bottom of the vice.

If you choose to make stepped dowels, the procedure is similar to making the keys, but involves turning rather than milling.

Turn the larger diameter first, then the smaller, without disturbing the material, so that the diameters are concentric.. Drill a clearance hole through the dowel, (If the larger diameter is that of the T slot, the first dowel will need to be parted off reversed in the chuck and counterbored.

Counterboring should be the last operation, before deburring, after both dowels have been turned to size.

Once the machining has been completed, the keys or dowels can be secured to the vice by means of cap, or countersunk, screws into the tappings in the bottom of the vice. If it needs to be said, the screws must not bottom out in the tappings before the key / dowel is firmly clamped in position..

Hopefully to slots in the vice will ensure that the fixed vice jaw is aligned with the T slot in the Table.



Paul Lousick11/01/2021 12:40:18
1648 forum posts
613 photos

Unless the keys are a transition or interference fit with the slots in both the vice and table there will always be some mis-alignment, so it is good practice to always push the vice against one side of the table slot as you are tightening the hold down bolts to keep them parallel. Even if the keys in the vice are much smaller than the mill table slots, you can align it fairly accurately by pushing against one side of the slot.

Using the keys to align the vice is only accurate if they are parallel to the jaws in the vice.


john halfpenny11/01/2021 12:54:06
110 forum posts
18 photos

I'm glad I read this post. My mill vice came with two blocks screwed to the back of the moving jaw. Now I know what they are and, to my surprise, they fit both the vice and the tee slot.

James Margrave14/01/2021 00:11:26
5 forum posts

Hi guys sorry for long delay! Been a very tough few days,


That's for all your replies,

Not done it yet, yes would normally ask / get him to do it but I've been quarantined for 10 days as work mate had covid and now my wife has it so again got to add on another 10 days (think I gave it to her but I've had no symptoms but got tested when she did and had it too but she was ill) so anyways getting and asking her brother was out the question at mo

Nick Farr yes thats it.

I've done some digging and yes the new vise has a slot in it with 2 pre drilled tapped holes. Ive bought some (tenons) keys that fit the vise (thanks for the info above and what they are called I managed to find a pack of 5) but unfortunately the lathe tee slots are around 1mm each side too narrow compared to the vise pre cut slot and the new keys,

Im going to mill the 1mm off that slicks out from the grove on the vise so it will line up.

Thanks for help above regards to a dial gauge yes I have one I will use to check my work after cutting the keys and as normal once fitted to check work is level and square before cutting. I could just bolt on and use dial gauge but my other problem is my cross slide isn't quite wide enough to put a t bolt at each end of the vise only 1 end so need atleast 1 key on the vise inorder to stop the vise moving at the end I can't clamp down, it's a big heavy vise so can't see it moving with just 1 tee bolt In but will have to check to make sure it doesn't then tilt the vise when done up

I could solve by putting a tee slotted plate onto my cross plate to make it bigger and will prob do this but for now thanks to your help I can aleast use it as is.

I've also discovered the ones I have for my rotary table I have to mill too but gives me something to do.

Edited By James Margrave on 14/01/2021 00:22:14

Nicholas Farr14/01/2021 10:20:19
2550 forum posts
1211 photos

Hi James, be aware that you may get some upward flexing of your vice during milling with it fixed with just one bolt, despite it being a heavy one. End mills and even drills will encourage the work to lift. It will be better to get or make a sub plate that you can fix to your cross slide with two bolts and then use two set screws to fix your vice to the sub plate and of course you can fix keys to the sub plate to go into the cross slide, and keys on top for your vice.

Regards Nick.

SillyOldDuffer14/01/2021 11:03:31
6681 forum posts
1501 photos

Just an observation: these key/tenons aren't worth bothering with in my workshop. As always it depends on what the machine is used for, but keys allow a vice to be positioned quickly rather than accurately, which doesn't ring my bell!

No problem with keys if rough alignment is 'good enough'. Otherwise, keys have to be fitted accurately and the owner has to make sure they don't move. In a knock about workshop that level of care may be unwelcome, and it may not be 'good enough' if a job really needs to be aligned as accurately as possible.

My workshop isn't rushed, and I work to moderate accuracy. I have a separate lathe and milling machine and don't use keys to position anything. Instead:

  • Vice, rotary table, or whatever is positioned roughly with an engineering set-square and nipped down gently with all the bolts or clamps,
  • Say it's a vice. I fit a DTI to the mill spindle and open the vice jaws. Then I position the table so the DTI registers against the fixed jaw and run along the edge using the other axis to see how much error the DTI measures over a distance. Say its 0.1mm over 100mm (poor). Halve the reading by tapping the vice gently on one side with a mallet so it swivels slightly under the loose bolts. Traverse back, remeasure and repeat traverse-tap until the DTI can't detect any error or it's small enough not to matter. Then tighten all the bolts so the vice can't move. Apart from taking time to do, this method is more accurate and it doesn't depend on setting up and maintaining keys. With practice a vice can be aligned in a few minutes.

Most of my milling is done with a vice which is often left aligned on the table for weeks on end. This may not suit a combination mill/lathe where the owner is constantly swapping. If so, I suggest setting the vice up as described above and using the mill to make suitable keys. Fit them to the vice, check alignment with the DTI, and fettle again as necessary. It may take several attempts to get the keys right, but at least you don't need keys to make keys and know they fit properly.

My inexpensive vices and rotary table are both grooved to take keys, but neither came with them, nor have I ever noticed keys being advertised, perhaps because they only come with posh kit or have to be bespoke to fit the slots in each machine. I'm not aware of a slot standard.


Edited By SillyOldDuffer on 14/01/2021 11:05:04

Howard Lewis14/01/2021 11:32:30
4143 forum posts
3 photos

If the vice is wider than the Cross Slide, you could always make up a wider sub table to fix to the Cross Slide, so that the vice is clamped to it on both sides. This will cost you a little headroom, and needs to be substantial enough not to flex, (So no 3 mm plate, 10 or 12 would be better ) The sub base would have to be clamped to the Cross Slide by countersunk Allen screws.

Sadly, this will decrease the accuracy of alignment, since you will now have two fits involved rather than one. The best is to make all the fits transition fits (as tight as possible ) to minimise risk of movement.

Ideally, the sub base should be located to the Cross Slide by tenons, before the slot(s ) are milled to take the tenons on the vice. In this way, the slot for the Vice tenons will be in the plane of a cutter in the milling head.

This allows you to ensure that the slot for the vice tenons does not coincide with those for the sub base. This may be an advantage, allowing the vice to be positioned in a slightly better position for use of the handle.




James Margrave14/01/2021 22:49:30
5 forum posts

Thanks guys, I need to get back into shed and check but I think the vise will fit if I put the vise base as 90deg and bolt along the length of the cross slide the swivel the vise 90 round and then align this so it's straight. This will also remove any miss alignment but I need to go test it if not yes there are sub tables I could fit.

I prob could have got a slightly smaller vise but a bigger vise is better fir my use as I can also use it on the big floor mount pillar drill too rather than having 2 different vise.

Will report and let you guys know how I get on as never know if someone else is in same position

Edited By James Margrave on 14/01/2021 22:50:39

Nicholas Farr15/01/2021 10:06:59
2550 forum posts
1211 photos

Hi James, that sounds like a good plan. yes

Regards Nick.

old mart15/01/2021 16:50:10
2472 forum posts
169 photos

A lot of people get by without the tennons and just use a dti to get the jaws parallel each time.

If you bolt down a block or straight piece of material to the bed aligned with the X. axis, you can fit the vise inverted and skim the tennons. After skimming, and removing the vise, it is advisable to recheck the alignment of the block just in case it has moved. I would only skim the rear face of the tennons as it is easier to push the vise away from you when tightening the tee bolts.


James Margrave16/01/2021 23:31:36
5 forum posts

Hi guys once again thanks for all the help and advise.

So I measured the vise and took a punt. It was a few mm wider than the cross slide if I put the vise at 90 degrees to the headstock so I bit the bullet and decide it would just fit this way and get both security bolts on.

I first measured the depth of the grove in the vise this was 2.35mm I then set the original vise up and put a 25mm mill bit in and set it up so the tenons would be cut leaving a 2.2mm step as my groves in the cross slide were 12mm and the tenons and vise grove14mm wide so they needed to be milled a tiny bit 1mm each side. This also ment the vise would sit flush and level on the cross slide as the tenons step would be 0.15mm into the vise grove.

I took a flat block so hight would be same everytime and set the first tenon up once leveled I then locked all the lathe up and just worked by cutting across the lathe so the step would be the same every time. I milled the 2 tenons on one side each taking off 1mm on each I then put each tenon in and milled the other side till it was 11.98mm wide. I then marked the side I knew was cut the same and fitted these tenons to the vise with the marks facing the same direction.

I then fitted the new vise at 90deg and rotated it on the swivel of the vise 90deg I then measured it all and got it dead square. I then marked the vise and the base of the vise, and removed and refitted 3 times each time re squaring the vise. The mark lined up everytime.

So the vise sits on sideways and then I have to rotate it 90deg on the vise swivel base. It dosnt give me the best spread of weight but as its such a big vise 6" jaws there is enough strength there not to work about the vise flexing if drilling something unlike a small 2" vise might. I can if needs be remove the swivel base of the vise and fit the vise directly to the cross slide if I'm really worried but this way I have no ease of squaring the vise up but would get the vise to be sat on the cross slide under the jaws if needed for drilling but as said given the size of the vise I dowt it would ever flex on the swivel base its a big heavy lump at 9-11kg

Ov if I use the vise it still needs squaring off everytime but it gets me 99% there by eye and is alot quicker to fit than if I didn't have tenons.

I've got to do the same with my clocking base but this does fit the other cross slide either way round.


Thanks for everyone's help its made it alot easier and also been good to get other ideas and a better understanding of alignment. And also the correct part names.

Edited By James Margrave on 16/01/2021 23:35:03

Edited By James Margrave on 16/01/2021 23:41:46

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