BK3 Burgess Bandsaw Fence Assembly

BK3 Table Fence

Having mentioned the BK3 fence in the Quorn bracket post I realised that I had not posted the details of my fence design for the BK3.  The fence and the two sets of bearing based guides make the BK3 a very accurate and dramatically more useful tool for the workshop.

The fence as supplied with the BK3 was tending towards a chocolate fireguard in its usefulness.   Here is a Fusion 360 pictorial of my design together with a dimensioned drawing.  Both can be downloaded by clicking on the associated PDF file link.

Fusion 360 view of the BK3 fence design
Fusion 360 view of the BK3 fence design
Dimensioned drawing of the BK3 fence assembly
Dimensioned drawing of the BK3 fence assembly

Here is the link to the  Fence Assembly Drawing v4 which has both these views in better detail.

BK3 Angle Setting Fence

This is a further addition to the BK3 in the form of an angular setting fence.  This uses an inset protractor scale liberated from one of the readily available workshop protractors as shown below.   These are roughly 92mm diameter.  

The body is made from three separately printed 3D parts, the sliding bar, the protractor holder and the pointer block.   

The sliding bar has been tweaked in dimensions to snuggly fit the slot in the BK3 table.  It has printed nut retaining cavities on the lower surface.   For this reason it should be printed upside down.  Likewise the pointer block has two locating ribs on the lower surface and debatably should also be printed upside down.  This does distort the pointer a little and so might need a clean up post printing.  Customise all the retaining screw lengths to ensure they do not protrude below the lower surface of the bar.   The rotational locking screw could be made a bit more elegant by making a knurled knob item.

The three STEP files and the Fusion 360 file are in this ZIP file. 

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Quorn cutter grinder tool holder support

I am slowly getting to understand how to manipulate and use my recently purchased Quorn tool cutter grinder.    One frustration that kept cropping up was the workhead assembly slip rotating on the bed bar. This usually happens when there is a need to slide the tool holder head back after a referencing action.  This messes up the reference setting.

I chanced upon a thread on the MEW forum where a John P had solved this problem with a parallel support bar assembly.   This utilised the 1/4″unused hole in the toolholder side wall.  There are a number of ways to fabricate this fixture but the important aspects are that it should be robust and must ensure a parallel motion along the support rod.

quorn cutter grinder tool head support bar
The cutter grinder tool head support bar mounted on my Quorn

I opted to model the bracket in Fusion 360.  As there will be little stress on the bracket in use I opted to mill it from 15mm cast aluminium to give a 12mm finishing depth.  Here is the pictorial view from the Fusion desktop.

Fusion 360 model of the Quorn cutter grinder tool head bracket
Fusion 360 model of the Quorn cutter grinder tool head bracket.  The bracket measures around 90mm end to end.

The bracket has a 5/8″ hole to match the Quorn table slider rod and a 10mm hole for the new parallel support rod (sorry about the mixed dimensions but my Quorn is an Imperial model and most of my stock is metric).   

Side #1 CAM operations are to clean up skim the stock top surface followed by profiling the two holes and the outside shape.  Side #2 is to invert the model and deck the excess material.   The clamping slots, the flat adjacent to the 5/8″ hole and the M4 tapped holes are all supressed in the CAM and manually cut post CNC operations.

The model has two tabs adjacent to the 10mm hole.  These have no relevance to the use of the bracket but are there to make the width of the model equal.  This negates the need to use soft jaws to hold the model when undertaking side 2 operations to deck off the excess stock material. The decking brings the model to 10mm finishing depth.   These two tabs could be ground off afterwards if desired. 

I did consider grub screw clamping of both bars but there was a danger of deforming the associated bars.   It was easier and more elegant to design slot clamps into the Fusion model. The clamping slits were cut post CNC machining on my BK3 bandsaw.   (Try cutting straight slots on a BK3 without a decent fence and support bearings.) The parallel nature of the finished model width as mentioned above makes this a simple process against the bandsaw fence.

The two M4 clamping screw holes are drilled prior to the slots being cut.  The holes are drilled 3.3mm through and then M4 through threaded.  After the slots are cut one half of each hole is clearance drilled to M4. 

The flat adjacent to the 5/8″ hole is the last ‘after CNC’ machining operation.  This flat gives the clearance needed to allow the bracket to slide under the Quorn toolholder referencing dial.

The gliding bar is mounted in the spare hole in the tool holder side wall.   This hole in my Quorn had been drilled 1/4″.   The rod profile was turned with a centre from 10mm silver steel to have the 1/4″ section and then a short section threaded M6.   Note that I also made a brass washer profiled to match the rear face of the through hole in the body.  Like most of the Quorn casting holes this had a step segmented surface aimed at stopping bolt head rotations.

Fusion 360 pictorial view of the assembly
Fusion 360 pictorial view of the assembly
Quorn cutter grinder tool head support components
Quorn cutter grinder tool head support components – this shows the bracket with support bar in place, supporting rod and profiled washer.

Mounted on the Quorn, the assembly sat nicely parallel, is very solid and stable and does an excellent job of stopping the head drooping.  My frustrations over this aspect of the Quorn are eased for the time being.

If any readers want the Fusion file or dimensioned drawings then add a comment below.

UPDATE : – The bracket should be rigid enough when 3D printed instead of machined from solid. Here is a ZIP file containing  the support bar clamp version v5 as a STEP file.  All the other parts are straightforward lathe operations.

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A 3D Printed Passive Demagnetiser using Neodymium magnets

I saw a recent post on the HomeMadeTools.net site from Tony Foale about using Neodymium magnets in a rotating holder to act as a demagnetiser. 

Tony made the holder from aluminium but from my point of view with Fusion and 3D printing facilities the idea lent itself to be run as a 3D print.  The finished device can be held in a lathe or drill press chuck using the central boss.  The boss does not have to be rigidly clamped as the magnets will grab and locate the assembly up to the chuck.   The magnets are very strong so be very careful as you bring the object to be demagnetised up to the lower surface or it will also get ‘grabbed’. 

Attached is a ZIP file containing the Fusion 360 file.   This is designed to take 10mm diameter magnets which will be a tight push into the mounting holes.   I used 10mm long magnets but smaller ones will probably work just as well. The magnet mounting holes have a 1mm thickness bottom surface.   The magnets need to be inserted with the alternating orientation as shown.  Tony made a circular ‘keeper’ for the bottom surface from a steel disc.  This reduces the attraction to swarf.   The ZIP file also contains a simple lid to fit over the top side to protect the holes from accumulating magnetic swarf.

Screen shot of the demagnetiser fusion file
Pictorial screenshot view from Fusion 360 of the demagnetiser 3D model

ZIP file download is on the link below and contains the body and lid as a Fusion file and as separate STEP files  – demagnetiser disc body and lid

A closing thought (which I haven’t tried …) but if all the magnets were in the disc the same way round would this act as a magnetiser to save having to stroke the item with a magnet ?

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An alternative Bull’s Foot file for clock plate smoothing

A Bull’s Foot file comes in various formats.  In its simplest form it is a small circular filing surface mounted at right angles to a handle.  Its common use is for making good after a clock plate has been re-bushed when there is a need to selectively finish the newly inserted bush material to be flush with the plate surface.  

The commercially made files sometimes have a curved lower surface or have a periphery ring or bordering parallel strips of metal to ensure that the filing action cannot go deeper than the existing plate surface level.  Without this the filing action would lead to unwanted scratching and disfigurement of the plate.

I have got around the commercial geometry by using a homemade flat filing surface with two protective spacing mediums.  To get quickly to somewhere near flush I use a piece of 35mm film (5 thou thickness) with a suitable hole punched in it glued or held over the bush. This protects the plate from a wider area of damage caused by my flat homemade Bull’s Foot.  There is graphical representation of the concept below.  This is a method suggested by William Smith and John Wilding in their various books.  If I want to get even closer to the plate surface I have some sticky backed shim material that is 1.2 thou thick that I stick around the bush.

Graphical representation of a Bull's Foot file in use

With the commercial items, the bush is filed until flush using an increasing finer grade abrasion on the Bull’s Foot disc.   This means having to have a number of different abrasive Bull’s Foot files.   These are unusually difficult to source and expensive to accumulate.

My solution to this is to have a few Bull’s foot metal ‘blanks’ to which I mount appropriate circles of different grades of wet and dry paper.   The chosen wet and dry is simply held in place on the ‘foot’ with double sided tape.

Homemade Bull's Foot files
Homemade Bull’s Foot files and handles

The blanks (no more than 12mm diameter) are made from a disc of 3mm ground flat stock  brazed onto a 3mm silver steel shaft.  Once brazing is complete the disc is trued in the lathe by gripping the shaft.   The shaft is then heated to allow bending at right angles and then mounted in a home made handle.   

The handle is around 75mm long and is made from 15mm wooden dowel with a strengthening collar made from a 15mm length of 15mm copper water pipe.  The dowel is turned down such that the collar is a push fit and a 3mm pilot hole is drilled in the end face.   After preparation the dowel is varnished with the collar in place.  These homemade handles get used on other tools around my workshop such as needle files and gravers.

I agree the wet and dry will not last for ever but it is a cost effective and flexible option to a box full of ‘proper but not used very often’ Bull’s Foot files.  An alternative to using wet and dry is to Araldite shaped pieces of broken files onto a similar shaft and handle concept.  These would last longer but once again more handles would be needed to cover the grades of file needed.  The spacer medium would still be required to protect the plate surface.

For those of you more adventurous there is an alternative handheld solution detailed on the Sherline website.

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Adding thrust bearings to the Myford Super 7 with Clough42 ELS fitted

Some time ago I documented my implementation of the Clough42 Electronic Leadscrew on my Myford Super 7 Big Bore lathe.   I also wrote up adding thrust bearings to the top slide and cross slide adjusters.   What remained outstanding was adding thrust bearings to the leadscrew.  While there is a commercial kit from Hemmingway Kits to install these, my implementation of the ELS involved a direct drive to the leadscrew at the tailstock end of the bed and made things difficult – I ran out of length on the leadscrew.

After considering the situation I opted to retain my ELS drive concept and gain space for the bearings by shaving metal from the Myford leadscrew bracket.  It is not an ideal modification as I am always very reticent about physically changing the structure of my machines.   Despite this I have to say it seems to have paid off and I now have a very stable and repeatable leadscrew feed from the ELS.  Here is a photo of the result.

modification to the leadscrew mounting for adding thrust bearings
The final assembly using the ELS drive concept to the end of the leadscrew and how space was made for thrust bearings to be fitted

I have added details of the modification to the original thrust bearing write up and this can be downloaded as a PDF from the link below.

Myford Super 7 Thrust Bearing Mods including leadscrew

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