By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Imperial Drawbar for a Metric BF20 Mill

All Topics | Latest Posts

Search for:  in Thread Title in  
Johannes Grabsch04/03/2016 08:12:30
avatar
22 forum posts
2 photos

I have a metric BF20 Mill with a M10 Drawbar, but also some old tooling with 3/8 threads in their MT2 Tapers. The supplier of the mill seems to be unable to supply me an original drawbar with the required imperial thread (they are metric only...)

Before I start making a replacement drawbar there should be an obvious solution: There are many variants of the BF20 type mill around, and I guess also some imperial mills. Does anybody know weather a drawbar from an imperial Warco WM18 mill would fit into a BF20?

Thanks

Johannes

Chris Evans 604/03/2016 10:20:51
avatar
2156 forum posts

Not sure of your machine but it sounds like a simple turning job to make one.

Roderick Jenkins04/03/2016 10:59:18
avatar
2376 forum posts
800 photos

Many people may want to close their eyes to the next bit surprise

You can put a 3/8" Whitworth tap down an M10 thread and get satisfactory engagement with a 3/8 BSW draw bar.

M10 = .393". 1.5mm pitch is 16.9tpi

3/8BSW = .375. 16tpi

A bit agricultural but it works on my mill.  The reverse, an M10 tap down a 3/8 BSW hole ought to work even better.

Sorry,

Rod

Edited By Roderick Jenkins on 04/03/2016 11:03:31

ASF04/03/2016 11:03:32
131 forum posts
12 photos

I made one for my, similar, mill. A little bit more than a simple job though to be fair (well for me!). I found that, because of the length, you need to turn with tailstock support (probably obvious) but needed to use a travelling steady to ensure it was true down the entire length. I case hardened the squared end, as my original metric one had been.

Ian Parkin04/03/2016 11:36:12
avatar
1174 forum posts
303 photos

I recently went down a similar route with a selection of MT3 tooling all with different threads

I made them all the same to M12

Sometimes drilling out to retap and sometimes 1/2" whit just running a m12 tap down

a few needed annealing beforehand

 

if you want a drawbar in 3/8ths i have one for a wm18 machine

Edited By Ian Parkin on 04/03/2016 11:37:48

HOWARDT04/03/2016 11:59:33
1081 forum posts
39 photos

Why not just pin a nut, or special end onto some studding. Simpler and no long turning problems.

SillyOldDuffer04/03/2016 12:07:54
10668 forum posts
2415 photos
Posted by Roderick Jenkins on 04/03/2016 10:59:18:

Many people may want to close their eyes to the next bit surprise

You can put a 3/8" Whitworth tap down an M10 thread and get satisfactory engagement with a 3/8 BSW draw bar.

M10 = .393". 1.5mm pitch is 16.9tpi

3/8BSW = .375. 16tpi

A bit agricultural but it works on my mill. The reverse, an M10 tap down a 3/8 BSW hole ought to work even better.

Sorry,

Rod

Edited By Roderick Jenkins on 04/03/2016 11:03:31

 

It does! I would never have admitted to doing such a terrible thing without Rod's brave example. Perhaps we should start a "True Confessions" thread.

Cheers,

Dave

Edited By SillyOldDuffer on 04/03/2016 12:09:24

Johannes Grabsch04/03/2016 14:56:27
avatar
22 forum posts
2 photos

I had already considered cutting M10 threads into the imperial tooling. But unfortunately the very item that I need to use has a taper that appears to be hardened, so tough is it.

The drawbar of the Optimum BF20 is a tricky item. I could just use a long 3/8" threaded rod, but I would loose the safe feature to push out the tool from the spindle. As ASF said, simply copying the original drawbar but with an imperial thread is a bit more complicated than it sounds.

I think I'll buy a spare metric drawbar and I'll braze a length of 3/8 threaded rod replacing the M10 section.

Johannes

John Fielding04/03/2016 15:06:56
235 forum posts
15 photos

I have the same machine except it is the Rong Fu RF-25 as they are the makers. I have made plenty of drawbars for various bits of tooling. I use studding rod (all-thread) and sliver solder or cross pin a normal nut on the end and cut it to length. I sometimes need to make a thick washer cum stepped collar to fit the top of the quill where it comes through the top pulley. The original drawbar that was supplied seemed to be made from putty, very poor steel, the common or garden studding sells for almost nothing and makes at least two from a standard length.

Ian Parkin04/03/2016 15:18:30
avatar
1174 forum posts
303 photos

Johannes

heat the end of the taper up with a propane gas blowtorch untill its a red colour let it cool and you will be able to machine it then

I have not noticed any difference in the performance of my tooling....hardened or not on the taper

Ian S C05/03/2016 10:16:14
avatar
7468 forum posts
230 photos

I needed a 3/8W draw bar for my mill, took two bolts, cut the heads off, welded them together, the top end has a loose nut, and above that a pair of nuts jambed together, been ok for the last twenty odd years.

Ian S C

Howard Lewis05/03/2016 10:32:06
7227 forum posts
21 photos

+1 for making a 3/8 BSW drawbar. The one that came with my RF25 has the hexagon pinned to the top end.

So no reason why not to cut a 3/8BSW male on the end of a 3/8" or 19mm bar, and pin or weld a bit of hexagon bar on the other end, at the required distance.

(Not REALLY happy at hybridising threads, have come a cropper at times doing things like that)

And it is only a simple turning job to make a 3/8 BSW drawbar, anyway, so time well spent.

Howard

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate